Showing posts with label adoption. Show all posts
Showing posts with label adoption. Show all posts

Sunday, March 10, 2019

IQ of biracial children and adults



First snow in Minnesota (c. 1895), Robert Koehler. Biracial children have IQ scores halfway between those of white children and black children, even when they are conceived by white single mothers and adopted into middle-class white families in their first year of life.



You may have heard about the Minnesota Transracial Adoption Study. It was a longitudinal study of black, biracial, and white children adopted into white middle-class Minnesotan families, as well as the biological children of the same families (Levin, 1994; Lynn, 1994; Scarr and Weinberg, 1976; Weinberg, Scarr, and Waldman, 1992). IQ was measured when the adopted children were on average 7 years old and the biological children on average 10 years old. They were tested again ten years later. Between the two tests, all four groups declined in mean IQ. On both tests, however, the differences among the four groups remained unchanged, particularly the 15-point gap between black and white adoptees. 

The biracial children remained halfway between the black and white adoptees. Could this be due to the parental environment being likewise half and half? Well, no. All of them were raised by white parents, and they were adopted at an early age: 19 months on average for the white adoptees, 9 months for the biracial adoptees, and 32 months for the black adoptees. The last figure is emphasized by Scarr and Weinberg (1976) as a reason for the IQ gap between the black and white adoptees. 

Fine, but what about the IQ gap between the biracial and white adoptees? Almost all of the biracial children were adopted at a young age and born to white single mothers who had completed high school. From conception to adulthood they developed in a "white" environment. If anything, the white adoptees should have encountered more developmental problems because they were adopted at an older age.

Could color prejudice be a reason? Perhaps the biracial children were unconsciously treated worse than the white children. By the same reasoning, they may have been treated better than the black children. We can test the second half of this hypothesis. Twelve of the biracial children were wrongly thought by their adoptive parents to have two black parents. Nonetheless, they scored on average at the same level as the biracial children correctly classified by their adoptive parents (Scarr and Weinberg 1976).


The Eyferth study

Another study found no difference in IQ between white and biracial children. This was a study of children fathered by American soldiers in Germany and then raised by German mothers (Eyferth 1961). It found no significant difference in IQ between children with white fathers and children with black fathers. Both groups had a mean IQ of about 97.

These findings were criticized by Rushton and Jensen (2005) on three grounds:

1. The children were still young when tested. One third were between 5 and 10 years old and two thirds between 10 and 13. Since IQ is strongly influenced by family environment before puberty, a much larger sample would be needed to find a significant difference between the two groups.

2. Between 20 and 25% of the “black” fathers were actually North African.

3. At the time of the study, the US Army screened out low IQ applicants with its preinduction Army General Classification Test. The rejection rate was about 30% for African Americans and 3% for European Americans. African American soldiers are thus a biased sample of the African American population.

Another factor is that the capacity for intelligence seems to be more malleable in children than in adults. We see this with the Minnesota Transracial Adoption Study. In the enriched learning environment of middle-class Minnesota families, all of the children showed impressive IQ scores at 7 years of age. By 17 years of age, however, this benefit had largely washed out:

-------------------- Age 7 Age 17

Black children ----- 97 ----- 89

Biracial children - 109 ----- 99

White children --- 112 ---- 106

Does intelligence really decline with age because of wear and tear on the brain? Perhaps we’re programmed to be most intelligent in childhood. That’s when we have to familiarize ourselves with the world. The capacity for intelligence may then be gradually deactivated as we get older because it’s less necessary.

This deactivation may follow different trajectories in different human groups. In early Homo sapiens, it may have begun not long after puberty. As ancestral humans made the transition to farming, sedentary living, and increasingly complex societies, this learning capacity became more necessary in adulthood, with the result that natural selection favored those individuals who retained it at older ages. This gene-culture coevolution would have gone farther in some populations than in others.


The Fuerst et al study

A recent study led by John Fuerst has confirmed the intermediate IQ of biracial individuals, this time in adults. The research team used the General Social Survey, which includes not only ethnic, sociological, and demographic data but also a measure of intelligence (WordSum):


The relationship between biracial status, color, and crystallized intelligence was examined in a nationally representative sample of adult Black and White Americans. First, it was found that self-identifying biracial individuals, who were found to be intermediate in color and in self-reported ancestry, had intermediate levels of crystallized intelligence relative to self-identifying White (mostly European ancestry) and Black (mostly sub-Saharan African ancestry) Americans. The results were transformed to an IQ scale: White (M = 100.00, N = 7569), primarily White-biracial (M = 96.07, N = 43, primarily Black-biracial (M = 94.14 N = 50), and Black (M = 89.81, N = 1381).

The same study also found a significant negative correlation among African Americans between facial color and WordSum scores. The correlation was low (r = -0.102), but it would be difficult to get a higher correlation because of the measures used. Self-reported skin color correlates imperfectly with actual skin color, which in turn correlates imperfectly with European admixture. Wordsum likewise correlates imperfectly with IQ (r = 0.71). On a final note, the correlation between facial color and WordSum scores was not explained by region of residence, interviewer’s race, parental socioeconomic status, or individual educational attainment.


References

Eyferth, K. (1961). Leistungen verscheidener Gruppen von Besatzungskindern in Hamburg-Wechsler Intelligenztest für Kinder (HAWIK). Archiv für die gesamte Psychologie 113: 222-241.

Fuerst, J.G.R., R. Lynn, and E.O.W. Kirkegaard. (2019). The Effect of Biracial Status and Color on Crystallized Intelligence in the U.S.-Born African-European American Population. Psych 1(1): 44-54. https://dx.doi.org/10.3390/Psychology1010004

Levin, M. (1994). Comment on the Minnesota transracial adoption study. Intelligence 19: 13-20.

Lynn, R. (1994). Some reinterpretations of the Minnesota Transracial Adoption Study. Intelligence 19: 21-27.

Rushton, P. and A.R. Jensen. (2005). Thirty years of research on race differences in cognitive ability. Psychology, Public Policy, and Law 11: 235-294.

Scarr, S., and Weinberg, R.A. (1976). IQ test performance of Black children adopted by White families. American Psychologist 31: 726-739.

Weinberg, R.A., Scarr, S., and Waldman, I.D. (1992). The Minnesota Transracial Adoption Study: A follow-up of IQ test performance at adolescence. Intelligence 16: 117-135.

Saturday, October 3, 2015

The adaptive value of "Aw shucks!"


Solitude - Frederic Leighton (1830-1896)

 


In a mixed group, women become quieter, less assertive, and more compliant. This deference is shown only to men and not to other women in the group. A related phenomenon is the sex gap in self-esteem: women tend to feel less self-esteem in all social settings. The gap begins at puberty and is greatest in the 15-18 age range (Hopcroft, 2009).

Do women learn this behavior? Why, then, do they learn it just as easily in Western societies where constraints on female behavior are much weaker and typically stigmatized?

In U.S. society most of the formal institutional constraints on women have been removed, and ideologies of the inferiority of women are publicly frowned on. Sexual jealousy is also publicly disapproved, however much private expectation there may be of the phenomenon. Resources inequalities between men and women have also been reduced, although not eradicated. Certainly, male violence against women is still a reality and may play a role promoting deference behaviors in college-aged women. However, it seems unlikely that fear of physical violence is enough to explain why young women typically defer to men when involved in non-sex typed tasks in experimental settings. (Hopcroft, 2009)

Moreover, why would this behavior be learned mainly between 15 and 18 years of age?

[...] by many measures, girls at this age in the United States are doing objectively better than boys — they get better grades, have fewer behavioral and disciplinary problems, and are more likely to go to college than boys (Fisher 1999: 82). Qualitative studies also show the decline in female confidence and certainty at adolescence (Brown and Gilligan 1992). Brown and Gilligan's (1992) study was done in an elite private girls' school among girls who were likely to have every opportunity in life. Why would their self confidence be eroded at puberty? Certainly, there are few differences in resources between teenage boys and girls. Brown and Gilligan (1992) argue that our sexist culture strikes at girls during puberty, stripping girls of their self esteem. It seems odd that our patriarchal culture should wait until that precise moment to ensnare girls. (Hopcroft, 2009)

Female self-esteem seems to be hormonally influenced. It declines at puberty, reaches its lowest levels in late adolescence, gradually increases during adulthood, and peaks after menopause.

[...] evidence from many cultures [shows that] post-menopausal women often enjoy a status equal to that of men: they become in effect "honorary men." [...] Even in the most gender restrictive societies they are freed from menstrual taboos and purdah, often begin to inherit property and acquire wealth, and in general have increased freedom, status, power and influence in society. A recent experimental study of influence in small groups showed that older women (50 and older) do not defer to older men, and that older men do not display lack of deference to older women. (Hopcroft, 2009)

Female deference varies not only over a woman's lifetime but also from one woman to the next, i.e., some women are more predisposed than others. This variability may exist for one or more reasons:

- Not enough time has elapsed for selection to remove contrary predispositions (non-deference) from the gene pool.


- The selection pressure is relatively weak: contrary predispositions appear through mutation as fast as they are removed through selection.


- The strength or weakness of selection may vary among human populations. Gene flow may reintroduce contrary predispositions from populations where the selection pressure against them is relatively weak.


- There may be frequency-dependent selection. Non-deferring women may be better liked when less common.

Sexual selection?

For all these reasons, evolutionary psychologist Rosemary Hopcroft (2009) argues that female deference is an innate predisposition and not a learned behavior. It has become widespread because sexual selection has favored deferential women. When women compete on the mate market, success goes to the more deferential ones.

One might point out that deferential behavior would be advantageous not only at the time of mating but also later—during pregnancy and infant care. So, strictly speaking, the selection pressure wouldn’t be just sexual selection.

But Hopcroft's argument is vulnerable to a more serious objection: sexual selection of females is the exception and not the rule in most animal species, especially mammals. The males are the ones that have to compete for mates. This reflects differing contributions to procreation, the female being saddled with the tasks of pregnancy, nursing, and early infant care. Meanwhile, the male is usually free to go back on the mate market, with the result that mateable males outnumber mateable females at any one time.

Hopcroft knows this but argues that the human species is a special case because "human fathers often invest heavily in their children." But often they don't. What about societies where men do very little to raise their offspring? This point doesn't disprove Hopcroft's argument. In fact, it may provide a way to prove it, i.e., female deference should be stronger where paternal investment is higher.

If we look at hunter-gatherers, paternal investment tends to follow a north-south cline. It's low in the tropical zone where women gather food year-round and can thus provide for themselves and their children with little male assistance. It's higher farther away from the equator, where winter limits food gathering and makes women dependent on food that men provide through hunting. Paternal investment is highest in the Arctic: almost all food is provided by men, and women specialize in tasks unrelated to food procurement (garment making, shelter building, meat processing).

This north-south cline was maintained and in some cases accentuated when hunting and gathering gave way to farming. In the tropical zone, farming developed out of female food gathering and thus became women's work, as is still the case in sub-Saharan Africa and Papua New Guinea. This sexual division of labor also explains why tropical farmers preferred to domesticate plants for food production. Only one animal species, the guinea fowl, has been domesticated in sub-Saharan Africa, and it was apparently domesticated by women. All other forms of livestock have come from elsewhere.

How universal is female deference?

Female deference should therefore vary within our species. In particular, it should correlate with the degree of paternal investment in offspring and, relatedly, the intensity of female-female competition for mates. This doesn't mean that women are actually more deferential in societies where men are providers. It simply means that they create an impression of deference, while continuing to do much of the real decision-making.

This issue is sidestepped by Hopcroft, who speaks only of 'women' and 'men'—as if all human groups show the same pattern of female deference. She cites many studies to prove her point, but this literature is overwhelmingly based on Euro-American or European participants. There is one study on African Americans, but it was limited to boys and girls 11 to 14 years old (Weisfeld et al., 1982).

In fact, this presumed universality of female deference was already disproven by a study published two years earlier:

Much feminist literature has described the relative silence of girls in classrooms and a concomitant drop in self-esteem for girls in their early teens (Sadker & Sadker, 1994; American Association of University Women, 1992). But other work has noted that Black girls maintain their self-esteem and their classroom "voice" into adolescence despite the fact that they may feel neglected in education (Orenstein, 1994; Taylor et al., 1995). (Morris, 2007)

Over a period of two years, Morris (2007) studied African American girls in grades 7 and 9 of an American middle school referred to as "Mathews." The students were 46% African American and the teachers two-thirds African American.

He found that African American girls seemed to feel little inhibition in the presence of boys:

Indeed, at Matthews I often observed girls—particularly Black girls—dominating classroom discussion.

[...] I noticed this active participation of girls to a greater extent in English classrooms, particularly when, as in this example, the subject concerned gender issues or relationships. However, the topic in this example also concerned computers and technology, areas more commonly dominated by boys. Furthermore, girls at Matthews, especially Black girls, spoke out to ask and answer questions in science and math classes as well, although to a lesser extent than in English and history classes. This willingness of African American girls to compete and stand up to others also emerged in their non-academic interactions with boys.

[...] Black girls at Matthews often challenged physical contact initiated by boys by hitting and chasing them back. They did not yield to and accept this behavior from boys, nor did they tend to seek adult authority to protect themselves and punish the boys.

[...] Thus, most African American girls in my observations did not hesitate to speak up in classrooms, and stand up to boys physically. Few Black girls I observed created disruptions in classrooms, but most consistently competed with boys and other girls to gain teachers' positive attentions.

[..] I observed this outspokenness at Matthews. Black girls there appeared less restrained by the dominant, White middle-class view of femininity as docile and compliant, and less expectant of male protection than White girls in other educational research.

These observations were consistent with those of the teachers, who generally described African American girls as being confrontational, loud, and unladylike:

Teachers, particularly women, often scolded Black girls for supposedly subverting their authority in the classroom.

 


[...] By far the most common description and criticism of African American girls by all teachers at Matthews was that they were too "loud."

[...] For many adults at Matthews, the presumed loud and confrontational behavior of African American girls was viewed as a defect that compromised their very femininity. This emerged most clearly in educators castigating Black girls to behave like "ladies."

Morris attributed this behavioral pattern to America's history of slavery and race relations. It would be useful to examine comparable data from sub-Saharan Africa. Do African women show less deference to men in mixed-gender settings?

According to a study of Akan society in Ghana, wives traditionally deferred to their husbands, but such deference was less common than in European society because social interactions were less frequent between husband and wife, being limited to certain areas of family life:

Traditional norms stipulated, for example, that the wife should not eat with the husband; that she alone must carry the foodstuffs from the farm; take water for the husband to the bathroom; sweep the compound; do the cooking; clean her husband's penis after sexual intercourse; and show deference to him in speech and action. (van der Geest, 1976)

Husbands and wives seldom made decisions jointly:

Joint decision-making is believed to be a departure from the past when decisions were made in a much more autocratic way by the husband alone or when spouses decided over their own matters separately (van der Geest, 1976).

Things were very different in mixed-gender settings outside the family. In the larger community, African women of all ages showed little deference to men, the situation being similar to that of older women in European societies.

Despite these outward rules, however, women held considerable power and commanded wide respect. They played a role in traditional politics and religion and were nearly always economically independent of their husbands. Moreover, women enjoyed a high degree of freedom to enter and to terminate marital unions, and in the matrilineal society of the Akan they were the focal points of descent lines. (van der Geest, 1976)

It is unclear to what degree modernization has changed these social dynamics. Van der Geest (1976) found much interest among younger Akan in the European model of family life, i.e., husband and wife eating and socializing together, and making decisions together. His own study, however, failed to find a significant difference between older and younger Akan in this respect. He concluded that the elite were moving toward European models of behavior, but not the majority of the population:

There are indications that—contrary to the situation in elite circles—marriage in lower socioeconomic groups remains an institution of secondary importance. Spouses have relatively low expectations of their marriage partners and of marriage in general. Men are often reluctant or unable to provide sufficient financial support for their families, and not infrequently women bear the burden of parenthood alone. [...] Wives remain more attached to their families of origin than to their partners, and in almost half of all cases husband and wife do not even constitute a residential unit. The relatively low status of marriage in Kwahu is perhaps best reflected in the high incidence of divorce and extramarital sex. (van der Geest, 1976)

This is consistent with findings from other studies. The pair bond is relatively weak in sub-Saharan Africa. Husband and wife tend to feel greater attachment to their respective kin. The husband is more certain that his sister's offspring are his blood relatives, whereas the wife sees her mother, sisters, and other female relatives as more reliable sources of child care.

Poewe found in her fieldwork that the marriage institution was highly flexible and discouraged strong, intense, or lasting solidarity between husband and wife. The male in these matrilineal societies did not produce for his progeny or for himself, but usually for a matrician with whom he might or might not reside. His role, as husband, was to sexually satisfy and impregnate his wife and to take care of her during her pregnancies, but under no circumstances should a man be the object of "exclusive emotional investment or focus of attention. Instead, women are socialized to invest their emotions and material wealth in their respective matrilineages." (Saidi, 2010, p. 16).

For this reason, European outsiders see parental neglect of children where Africans see no neglect at all—simply another system of child care. As Africans move to other parts of the world, they tend to recreate the African marriage system in their host countries by using local people and institutions as "surrogate kin." This is the case in England, where young African couples often place their children in foster homes:

The foster parents interpret the infrequent visiting of their wards' "real" parents as signs of parental neglect and become strongly attached to the foster children. This sometimes results in legal suits for transfer of custody to the foster parents (Ellis 1977). Meanwhile, the African parents make no comparable assumption that the delegation of care means they have surrendered formal rights in children. They consider that by having made safe and reliable arrangements for the care of children and by regular payment of fees, they are dispatching their immediate responsibility. (Draper, 1989, p.164)

In recent years, there has been much talk of an "adoption crisis" in Africa, where millions of children are not being raised by both parents and thus purportedly need to be placed in Western homes. Yet this situation is far from new. In fact, it's unavoidable in a culture where women cannot count on male assistance and have to make other arrangements:

In most African communities, the concept of "adoption" does not exist in the western sense. Children are fostered, a prevalent, culturally sanctioned procedure whereby natal parents allow their children to be reared by adults other than the biological parent [35] [36]. Child fostering is a reciprocal arrangement and contributes to mutually recognised benefits for both natal and fostering families [37]. In Tanzania, less than one quarter of children being fostered by relatives other than their biological parent were orphans. (Foster and Williamson, 2000).

Conclusion

Evolutionary psychologists believe that all human populations share the same genetic influences on behavior. They defend this belief by pointing to the complexity of behavior and the presumably long time it would take for corresponding genetic influences to evolve coherently from scratch. But why do they have to evolve from scratch? Evolution usually proceeds through minor modifications to what already exists. This is no less true for genetic determinants of behavior. For instance, an innate mental algorithm may be partially or completely deactivated. Or its range of targets may be broadened. Or it may deactivate more slowly with increasing age.

To the extent that human groups differ genetically in mental makeup, the differences are not due to some groups having completely new mental algorithms. Instead, the differences are due to the same algorithms being modified in various ways, often subtly so. For example, learning is primarily an infant behavior that becomes more difficult with increasing age. People may differ in learning capacity not because their learning algorithms differ but because these algorithms remain fully active for a longer time in some people than in others.

Another example may be female deference. In early modern humans, women tended to feel deferential in the presence of men, but this tendency was weak because a woman's interactions with her husband were infrequent and less important for her survival and the survival of her children. This is still the case in human groups that never left the tropical zone.

As humans spread beyond the tropics, this behavioral tendency became more easily triggered, particularly during the ages of 15 to 18 when young women entered the mate market. This evolutionary change came about because women in non-tropical environments were more dependent on men for food, particularly in winter. Women were, so to speak, in a weaker bargaining position than men, first of all on the mate market and later during pregnancy and infant care.

References

 


Brown, L.M., and C. Gilligan. (1992). Meeting at the Crossroads: Women's Psychology and Girls' Development, Harvard University Press.

http://fap.sagepub.com/content/3/1/11.short

 



Draper, P. (1989). African marriage systems: Perspectives from evolutionary ecology, Ethology and Sociobiology, 10, 145-169.

http://www.sciencedirect.com/science/article/pii/0162309589900174

Fisher, H. (1999). The First Sex, Random House.

 


Foster, G., and J. Williamson. (2000). A review of current literature of the impact of HIV/AIDS on children in sub-Saharan Africa, AIDS 2000, 14: S275-S284.

http://www.hsrc.ac.za/uploads/pageContent/1670/AreivewofcurrentliteratureontheimpactoforphansinAfrica.pdf

 



Hopcroft, R.L. (2009). Gender inequality in interaction - An evolutionary account, Social Forces, 87, 1-28.

https://www.researchgate.net/publication/236707130_Gender_Inequality_in_Interaction__An_Evolutionary_Account

 



Morris, E.W. (2007). "Ladies" or "Loudies"? Perceptions and experiences of black girls in classrooms, Youth & Society, 20, 1-26.

http://www.researchgate.net/profile/Edward_Morris7/publication/258200296_Ladies_or_Loudies_Perceptions_and_Experiences_of_Black_Girls_in_Classrooms/links/54be6b4e0cf218d4a16a60ac.pdf

 



Saidi, C. (2010). Women's Authority and Society in Early East-Central Africa, University of Rochester Press.

https://books.google.ru/books?id=_dQcIsFvkfwC&printsec=frontcover&hl=ru#v=onepage&q&f=false

 



van der Geest, S. (1976). Role relationships between husband and wife in rural Ghana, Journal of Marriage and the Family, 38, 572-578.

http://sjaakvandergeest.socsci.uva.nl/pdf/ghana/kwahu_marriage.pdf

 



Weisfeld, C.C., G.E. Weisfeld, and J.W. Callaghan. (1982). Female inhibition in mixed-sex competition among young adolescents, Ethology and Sociobiology, 3, 29-42.

Saturday, August 16, 2014

Getting the babes but not the babies


 




Still from the film Is Matrimony a Failure? (1922). Who's making more babies? "Good boys" or "bad boys"? Originally, the good boys were, thanks to parental monitoring of relations between single men and single women. The pendulum then swung toward the bad boys in the 1940s, only to swing back after the 1960s.

 


A recent Swedish study has found that "bad boys" are outbreeding "good boys":

Convicted criminal offenders had more children than individuals never convicted of a criminal offense. Criminal offenders also had more reproductive partners, were less often married, more likely to get remarried if ever married, and had more often contracted a sexually transmitted disease than non-offenders. Importantly, the increased reproductive success of criminals was explained by a fertility increase from having children with several different partners. (Yao et al., 2014)

This study has been much talked about, yet few people have noticed its one big flaw. Sweden has many citizens of foreign origin whose crime and fertility rates exceed those of the native population (Crime in Sweden, 2014; Landes, 2008). Reproductive success may thus correlate with criminality simply because both tend to be higher among non-natives than among natives. Admittedly, this alternate explanation had been foreseen by the authors of the study and they tried to correct for it:

We included variables potentially associated with both criminal and reproductive behavior as covariates. [...] Immigrant status has been associated with both rule breaking, primarily through associations with other familial and socioeconomic risk markers (Moehling & Piehl, 2009), and adherence to cultural norms influencing fertility and monogamy-related outcomes (Coleman, 2006). The migration register provided information on immigrant status defined as being born in Sweden or not. (Yao et al., 2014)

Unfortunately, country of birth is no longer a satisfactory proxy for cultural identity, at least not in Sweden's case. There is now a large Swedish-born population that self-identifies as Pakistani, Somali, or Afghan, including the youths who rioted in Malmö last year. The Swedish crime rate is influenced almost as much by the Swedish-born of foreign background as by the foreign-born:

During the period 1997-2001, 25% of the almost 1,520,000 offences for which a perpetrator was convicted were committed by people born in the Middle East or Eastern Europe, while almost 20% were committed by people with a foreign background who were born in Sweden. (Crime in Sweden, 2014)

If we could examine only people of Swedish descent, I doubt reproductive success would still correlate with criminality or, more exactly, with a tendency to "love and leave" one woman after another. Such a correlation used to exist in the U.S. but disappeared almost half a century ago. This was the conclusion of Jason Malloy and JayMan (2012) when they used General Social Survey data to find out the number of children fathered by monogamous men ("good boys") versus men who had several female sex partners ("bad boys"). It seems that the reproductive success of bad boys has varied a lot over time:

 


Men born before 1920 - courtship under parental supervision

 


In this cohort, good boys were the top breeders. No need to think hard to find the reason. Any man wishing to meet a single woman, other than a prostitute, had to run a gauntlet of parental supervision. The preferred form of courtship was still "calling." If a woman struck your fancy, you could "call" on her at her home. If she and her parents were favorably impressed, you could come back for further visits and eventually start taking her out to social events. Otherwise, that would be the end of it. A more direct approach could get you in big trouble, as a reference book for American lawmakers explained in 1886:

The state should punish, not only treacherous inducements to incontinence or to unchastity when accompanied by the violation of particular duties, and the seduction of minors, or girls under sixteen, but also seduction when it assumes a character dangerous to the interests of the community. It is not the duty of the state to make the individual moral, or to protect her against temptations to immorality; but it should endeavor to prevent all acts of immorality calculated to poison family life and the life of the nation. (Lalor, 1886, vol.III, p. 211)

The concern here is not just venereal disease, but also a family's genetic heritage. In the 19th century, people believed that a part of their essence was reincarnated in their children and grandchildren. Their concern over sex was fueled not by irrational hang-ups but by a very rational desire to maintain the integrity of their family line. Bad boys threatened that integrity, and it was not for nothing that many ended up in jail ... or at the end of a rope.

 


Men born between 1920 and 1939 - rise of dating, illegitimacy, and adoption

In this cohort, bad boys were the top breeders. Parental supervision had slackened with the replacement of calling by dating, thus creating new opportunities for them to sow their seed. A sharp rise in illegitimacy led to a sharp rise in adoption:

[...] The period 1945 to 1974, the baby scoop era, saw rapid growth and acceptance of adoption as a means to build a family. Illegitimate births rose three-fold after World War II, as sexual mores changed. Simultaneously, the scientific community began to stress the dominance of nurture over genetics, chipping away at eugenic stigmas. In this environment, adoption became the obvious solution for both unwed mothers and infertile couples. (Adoption, 2014)

Adoption had previously been very rare. As late as 1923, only 2% of children without parental care ended up in adoptive homes, the others going to foster homes or orphanages (Adoption, 2014). And a large chunk of that 2% involved adoptions between related families. These statistics are mirrored by my family tree: whenever children were left with no provider, they would be adopted by an aunt or an uncle or placed in a foster home. In those days, changing your family identity was as unthinkable as changing your religion or nationality.

To deal with the surge of illegitimacy, progressive-minded people now turned toward a seemingly great idea. On the one hand, there were babies abandoned by deadbeat dads. On the other, there were middle-class families with loving homes. Why not transfer these babies from the dads who don't love them to the ones who can?

The 20th century is littered with great ideas that proved to be not so great. Adoption is no exception. One negative outcome, which could have been foreseen, is that adopted children tend to replicate the psychological profile of their biological fathers. In one study, Gibson (2009) notes:

Adoptees were more likely than genetic offspring to have ever received public assistance, been divorced or been arrested. They also completed fewer years of schooling and were more likely to have ever required professional treatment for mental health, alcohol and drug issues.

[...] This supports other research showing that, compared to genetic children, American adoptees have a higher overall risk of contact with mental health professionals, specifically for eating disorders, learning disabilities, personality disorders and attention deficit hyperactivity disorder [...] They also have lower achievement and more problems in school, abuse drugs and alcohol more, and fight with or lie to parents more than genetic children [...]

These problems are not due to adoptive parents shortchanging adoptees. In fact, the reverse seems true:

This study categorically fails to support the hypothesis that parents bias investment toward genetically related children. Every case of significant differential investment was biased toward adoptees. Parents were more likely to provide preschool, private tutoring, summer school, cars, rent, personal loans and time with sports to adopted children. (Gibson, 2009)

Adoption does seem to improve the behavior of these children. It lowers their risk of committing violent crime, although they remain just as likely to commit other offences:

The possibility that genetic factors are among the causes of criminal behavior was tested by comparing court convictions of 14,427 adoptees with those of their biological and adoptive parents. A statistically significant correlation was found between the adoptees and their biological parents for convictions of property crimes. This was not true with respect to violent crimes. There was no statistically significant correlation between adoptee and adoptive parent court convictions. Siblings adopted separately into different homes tended to be concordant for convictions, especially if the shared biological father also had a record of criminal behavior. (Mednick et al., 1984)

With respect to intellectual capacity, adoptees likewise seem to benefit from their new homes, although the benefit tends to wash out over time. When children with two white biological parents were adopted into white middle-class homes, they initially did somewhat better than their non-adopted siblings, as seen on IQ tests at the age of 7. By the age of 17, however, the situation had reversed, with the adoptees falling behind their non-adopted siblings in terms of IQ, GPA, class ranking, and school aptitude (Minnesota Transracial Adoption Study, 2014).

Clearly, adoptees are getting some benefit although the benefit is less than what some may think. It also comes at a price. When the family unit is reoriented toward social welfare goals, it can no longer serve its original purpose of perpetuating a genetic heritage.

 


Men born after 1939 - separation of sex from reproduction

In this cohort, good boys have once again been the top breeders. This might seem counterintuitive. After all, sexual morality has become even more liberal since the 1960s, and this change has paralleled a growing infatuation with thuggish males in popular culture. Yet something seems to have kept bad boys from translating their sexual success into reproductive success.

That "something" is easier access to contraception and ... Roe v. Wade. More and more good girls are making out with bad boys, but fewer and fewer are making babies with them.

Pro-lifers see this as proof that pro-choicers are secret eugenicists. I think it's just an unintended consequence. Paradoxically as it may seem, modern culture is favoring the reproduction of stable couples who plan for the long term and invest in their children.

 


Just think. What is the core message of modern culture? It's live for today, live for yourself, and avoid long-term commitments, such as family and children. And who responds the most to that message? It's people whose time orientation is already focused on the present and who already invest as little as possible in their offspring. Modern culture is sterilizing those individuals who are most susceptible to its message.

And so, when it comes to having babies and raising them to adulthood, America's white middle class is slowly but surely closing in on first place (Frost, 2012).

 


Conclusion

Perhaps this is all for the best. What other choices are there? Conservative politicians talk a lot about traditional values, but not one in ten believe what they say. To judge by their personal lives, many seem happy with the current climate of sexual permissiveness. Anyhow, if conservatives really do try to turn back the clock, their efforts will be blocked by the libertarian right and the liberal left. And if they manage to outflank both groups, they'll be lucky to take us back to the policies and practices of the 1950s. Unfortunately, this is one case where half-measures will make things worse. We've come to where we are because of the 1950s.

 


So what political option is left for someone like me? I wish to preserve our existing genetic heritage, if only because we don't fully understand what we are about to lose. If you feel the same way, the best course of action seems to be the present one of separating sex from reproduction. Call it "tactical liberalism" if you wish, but I see no other realistic alternative.

 


References

 


"Adoption" (2014) Wikipedia

http://en.wikipedia.org/wiki/Adoption

 



"Crime in Sweden" (2014). Wikipedia

http://en.wikipedia.org/wiki/Crime_in_Sweden

 



Frost, P. (2012). Obama: White America's bogeyman? Evo and Proud, November 24

http://evoandproud.blogspot.ca/2012/11/obama-white-americas-bogeyman.html

 



Gibson, K. (2009). Differential parental investment in families with both adopted and genetic children, Evolution and Human Behavior, 30, 184-189.

http://anthro.vancouver.wsu.edu/media/Course_files/anth-260-edward-h-hagen/evil_step-parents.pdf

 



JayMan. (2012). Some guys get all the babes - not exactly, JayMan's Blog, November 8

http://jaymans.wordpress.com/2012/11/08/some-guys-get-all-the-babes-not-exactly/

 



Lalor, J.J. (1886). Cyclopaedia of Political Science, Political Economy, and of the Political History of the United States, Chicago: A.H. Andrews & Co.

http://books.google.ca/books?hl=fr&lr=&id=AsM6AAAAIAAJ&oi=fnd&pg=PA1&dq=Cyclopaedia+of+Political+Science,+Political+Economy,+and+of+the+Political+History+of+the+United+States&ots=VqItRo_7kY&sig=aL3srydNpIpMoKOlKnd5gXqnp0g#v=onepage&q=Cyclopaedia%20of%20Political%20Science%2C%20Political%20Economy%2C%20and%20of%20the%20Political%20History%20of%20the%20United%20States&f=false

 



Landes, D. (2008). Higher birth rates among Sweden's foreign born, The Local, November 3

http://www.thelocal.se/20081103/15408



Mednick, S.A., W.F. Gabrielli Jr., & B. Hutchings. (1984). Genetic influences in criminal convictions: evidence from an adoption cohort, Science, 224, 891-894

http://www.sciencemag.org/content/224/4651/891.short

 



"Minnesota Transracial Adoption Study" (2014), Wikipedia

http://www.sciencemag.org/content/224/4651/891.short



Yao, S., N. Langstrom, H. Temri, and H. Walum. (2014). Criminal offending as part of an alternative reproductive strategy: investigating evolutionary hypotheses using Swedish total population data, Evolution and Human Behavior, in press

http://www.ehbonline.org/article/S1090-5138%2814%2900077-4/abstract

Wednesday, December 16, 2009

The Montreal massacre. Part II

In debating the causes of the Montreal Massacre, we must confront the psychological similarities between Marc Lépine and his father. Both seem to have had low thresholds for ideation and expression of violence. Was this quick temper passed down from father to son? Or are the similarities only fortuitous?

If these psychological characteristics had passed down from father to son, they could have done so in only one of two ways. The preferred explanation is some kind of role-model conditioning, i.e., Marc Lépine looked to his father as a model for future behavior. But this seems unlikely. Marc hated his father. He repeatedly said so and reproached his mother for not doing enough to protect him from his father’s rage. Nor did he try to renew contact with his father after his parents broke up.

We’re thus left with some kind of unconscious conditioning that occurred before the age of 7 (when his parents broke up) and then began to express itself after puberty. But this too seems unlikely. For one thing, it implies a kind of infancy determinism that is no longer widely accepted in child psychology (Harris, 1998; Kagan, 1996; Kagan, 1998). As Jerome Kagan (1996) points out:

If orphans who spent their first years in a Nazi concentration camp can become productive adults (Moskovitz, 1983) and if young children made homeless by war can learn adaptive strategies after being adopted by nurturing families (Rathbun, DeVirgilio, & Waldfogel, 1958; Winick, Meyer, & Harris, 1975), then one can question the belief that the majority of insecurely attached l-year-olds are at high risk for later psychological problems. Even the behavioral differences among animals in laboratory settings are not very stable from infancy to reproductive maturity: "The findings offer meager support for the idea that significant features of social interactions at maturity are fixed by experiences in early development" (Cairns & Hood, 1983, p. 353). This conclusion affirms a discovery, now more than 20 years old, that even the stereotyped, bizarre social behaviors of 6-month-old isolated macaques can be altered by placing them with younger female monkeys over a 26-week period (Suomi & Harlow, 1972). These facts are also in accord with data on humans. Werner and Smith (1982), who followed a large sample of children from infancy to early childhood, concluded, "As we watched these children grow from babyhood to adulthood, we could not help but respect the self-righting tendencies within them that produced normal development under all but the most persistently
adverse circumstances" (p. 159).

For another thing, children behaviorally resemble their parents even if removed from parental influence shortly after birth. When adopted children are compared with their biological parents, we see moderate to high heritability in transmission of male aggressiveness (Baker et al., 2007; Barker et al., 2009; Rhee and Waldman, 2002). Furthermore, the non-genetic factors seem largely unrelated to parental influence, being either peer pressure outside the home or developmental accidents before and after birth (Harris, 1998).

Thus, to explain the psychological similarities between Marc Lépine and his father, the likeliest cause is genetic transmission. Either that or the similarities are just fortuitous.

The latter possibility should not be ruled out. When Monique Lépine sued for divorce, Rachid Gharbi strenuously denied her claims that he had abused their son. So perhaps we’re hearing just one side of the story. Remember, these proceedings happened before the liberalization of Canada’s divorce laws. Monique had to provide evidence of abuse to get her divorce.

To find out Rachid Gharbi’s side of the story, I turned to an article by an Algerian author on the “Impact of parental upbringing on child development.” The author’s first point is that Algerian upbringing is sex-specific. In boys, violent behavior is accepted and even encouraged:

In Algerian society for example, children are raised according to their sex. A boy usually receives an authoritarian and severe type of upbringing that will prepare him to become aware of the responsibilities that await him in adulthood, notably responsibility for his family and for the elderly. This is why a mother will allow her son to fight in the street and will scarcely be alarmed if the boy has a fall or if she sees a bruise. The boy of an Algerian family is accustomed from an early age to being hit hard without whimpering too much. People orient him more toward combat sports and group games in order to arm him with courage and endurance—virtues deemed to be manly. (Assous, 2005)

The purpose of this upbringing is not to suppress male aggressiveness but rather to channel it in the right direction: loyalty to the family and to tradition:

It is true that, in Arab and Muslim culture, parents are encouraged to discipline a child and to teach him obedience and submission by first using methods of communication and patience, but in the case of rebellion and especially of non-respect of Islamic laws it is recommended to use corporal punishment (e.g., a child who does not practice prayer is reprimanded as early as 10 years of age). (Assous, 2005)

Parental control is especially problematic after puberty:

Thus, during adolescence for example, the child will become more and more difficult to control. This behavioral disorder evidently pushes the parents to display more ill treatment in their authority and the schoolteachers to be more severe. (Assous, 2005)

The author presents an analysis of this corporal punishment, on the basis of cases brought to the notice of hospital authorities:

- it is directed much more at boys than at girls, by a ratio of almost 3 to 1

- it is inflicted (in order of importance) by schoolteachers, parents, neighbors, and other relatives

- it usually involves the use of blunt, non-cutting objects: a belt, a pipe, or a wire

- it is directed (in order of importance) at the head, arms or legs, belly, and chest

- the injuries (in order of importance) are multiple fractures, bruises, burns, scratches, and bites

The author goes on to note:

In Algerian society, even today, the absolute authority of parents over their children is seldom called into question by adults if it is exercised judiciously and without apparent adverse effects, and even though it often happens that more or less serious incidents cannot be avoided by parents in the grip of an intense anger that they cannot manage to control. (Assous, 2005)


Clearly, Rachid Gharbi and Monique Lépine had different notions of how young boys should be brought up. Monique came from a cultural background where corporal punishment is a last resort and usually takes the form of spanking. The preferred form of punishment is shaming: the boy is made to realize that he has done something wrong. At that point, his sense of shame will do the rest. If the boy has no sense of shame, he is considered to be abnormal, if not mentally ill.

In contrast, Algerian parents use shaming mainly to control girls. For boys, it seems to be at best a secondary or even tertiary means of control, the main ones being the threat and use of corporal punishment.

Why is child discipline so different in Algeria? The reason seems to be that violence is much more omnipresent. The average Algerian male is more ready and willing to use violence preemptively or in self-defense. Social peace is maintained largely by an implicit balance of terror: violence is deterred by the threat of retaliation—if not by the victim, then by a male relative. Evidently, the balance cannot always be maintained...

This aspect of Algerian life is described by Frantz Fanon in Les damnés de la terre:

It’s a fact, the magistrates will tell you, that four fifths of the cases heard involve assault and battery. The crime rate in Algeria is one of the highest in the world, they claim. There are no petty delinquents. When the Algerian, and this applies to all North Africans, puts himself on the wrong side of the law, he always goes to extremes (Fanon, 2004, p. 222)

The act of violence itself shows less restraint and the precipitating causes seem banal:

Autopsies undeniably establish this fact: the killer gives the impression he wanted to kill an incalculable number of times given the equal deadliness of the wounds inflicted.

… Very often the magistrates and police officers are stunned by the motives for the murder: a gesture, an allusion, an ambiguous remark, a quarrel over the ownership of an olive tree or an animal that has strayed a few feet. The search for the cause, which is expected to justify and pin down the murder, in some cases a double or triple murder, turns up a hopelessly trivial motive. Hence the frequent impression that the community is hiding the real motives.
(Fanon, 2004, p. 222)

The reason for this state of affairs ultimately goes back to the recentness of central authority in Algeria. Before the French conquest in the 19th century, each family depended on its male members to defend its interests. There were law courts, but they had no power to enforce their rulings. It was up to the aggrieved party to do the enforcement.

This situation was not unique. In fact, it was typical of all human societies and remains so in many parts of the world today. It changed only with the rise of central authority and its monopoly on the use of violence. With this change, the State put an end to the worst sort of tyranny: the daily fear of being assaulted or even killed, not by a foreign invader but by someone in your own town or village. The violent male went from hero to zero.

Initially, people complied with the new order by changing their behavior within the limits of phenotypic plasticity. The result was a more peaceful society where violent males were less often imitated, celebrated, and accommodated. This shift in the mean phenotype then contributed to a slower but similar shift in the mean genotype, by creating an environment that favored the reproduction of certain individuals at the expense of others. There was thus Baldwinian selection for individuals less predisposed to violence and more predisposed to submissiveness.

This process is described by the historical economist Gregory Clark with respect to England. Once central authority had become established, male homicide fell steadily from the twelfth century to the early nineteenth. Meanwhile, there was a parallel decline in blood sports and other forms of exhibitionist violence (cock fighting, bear and bull baiting, public executions) that nonetheless remained legal throughout this period. Clark ascribes this behavioral change to the reproductive success of upper- and middle-class individuals who differed statistically in their predispositions from the much larger lower class, including predispositions to violence. Although initially a small minority in medieval England, such individuals grew in number and their descendants gradually replaced the lower class through downward mobility. By the nineteenth century, their lineages accounted for most of the English population (Clark, 2007, pp. 124-129, 182-183; Clark, 2009).

Reference

Assous, A. (2005). L’impact de l’éducation parentale sur le développement de l’enfant, Hawwa, 3(3), 354-369.

Baker, L.A., K.C. Jacobson, A. Raine, D.I. Lozano, and S. Bezdjian. (2007). Genetic and environmental bases of childhood antisocial behavior: a multi-informant twin study, Journal of Abnormal Psychology, 116, 219-235.

Barker, E.D., H. Larson, E. Viding, B. Maughan, F. Rijsdijk, N. Fontaine, and R. Plomin. (2009). Common genetic but specific environmental influences for aggressive and deceitful behaviors in preadolescent males, Journal of Psychopathology and Behavioral Assessment, 31, 299-308.

Clark, G. (2009). The indicted and the wealthy: surnames, reproductive success, genetic selection and social class in pre-industrial England,
http://www.econ.ucdavis.edu/faculty/gclark/Farewell%20to%20Alms/Clark%20-Surnames.pdf

Clark, G. (2007). A Farewell to Alms. A Brief Economic History of the World, Princeton University Press, Princeton and Oxford.

Fanon, F. (2004). The Wretched of the Earth, New York: Grove Press.

Harris, J. R. (1998). The nurture assumption: Why children turn out the way they do, Free Press.

Kagan, J. (1998). Three Seductive Ideas, Cambridge, Harvard University Press.

Kagan, J. (1996). Three pleasing ideas, American Psychologist, 51, 901-908.

Rhee, S.H., and I.D. Waldman. (2002). Genetic and environmental influences on antisocial behavior: A meta-analysis of twin and adoption studies, Psychological Bulletin, 128, 490-529.

Thursday, December 10, 2009

The Montreal massacre ... 20 years later

On December 6, 1989, a 25-year-old man walked into Montreal’s École polytechnique and murdered fourteen women. The event is still being debated … twenty years later.

We know the immediate cause. The murderer, Marc Lépine, felt that places like the École polytechnique were training women to take jobs that had been mainly held by men like himself. In April 1989 he had met with a university admissions officer and complained about how women were taking over the job market. Earlier still, he had spoken out to men about his dislike of feminists, career women, and women in traditionally male occupations such as the police, saying that women should remain at home and care for their families. This resentment may have been exacerbated by his inability to find a girlfriend. He was generally ill at ease around women, tending to boss them around and showing off his knowledge in front of them

For many people, the debate stops there. Marc Lépine resented women, especially ‘feminists’, and this resentment led to the Montreal massacre. For others, such resentment does not in itself explain what happened. Lépine’s personal history points to a longstanding tendency toward asociality, short-temperedness, and ideation of violent behavior, particularly after he reached puberty in the late 1970s:


Late 1970s – When his sister made fun of him for not having a girlfriend, he fantasized about her death and made a mock grave for her.

September 1981 – He applied to join the Canadian Armed Forces as an officer cadet but was rejected during the interview process because he seemed antisocial and unable to accept authority.

1982-84 – At junior college, colleagues saw him as being nervous, hyperactive, and immature.

1987 – He lost his job at a hospital because of aggressive behavior, disrespect of superiors, and carelessness in his work. He was enraged at his dismissal, and at the time described a plan to go on a murderous rampage and then commit suicide. His friends said he was unpredictable and would fly into rages when frustrated.

Some people trace this behavioral pattern to his early childhood, specifically as the son of a Catholic French-Canadian mother, Monique Lépine, and a Muslim Algerian father, Rachid Liass Gharbi. The latter’s psychological profile looks very similar to Marc Lépine’s:

Gharbi was an authoritarian, possessive and jealous man, frequently violent towards his wife and his children. Gharbi had contempt for women and believed that they were only intended to serve men. He required his wife to act as his personal secretary, slapping her if she made any errors in typing, and forcing her retype documents in spite of the cries of their toddler. He was also neglectful and abusive towards his children, particularly his son, and discouraged any tenderness, as he considered it spoiling. In 1970, following an incident in which Gharbi struck his son so hard that the marks on his face were visible a week later, his mother decided to leave. (Marc Lépine - Wikipedia)


His mother had divorced his father over the issue of abuse, which had extended to the children. Beaten by his father, Rachid Liass Gharbi, for such minor problems as singing too loudly or failing to greet him in the morning, Lépine had learned to fear him.

"He was a brutal man," Monique Lépine told the court, "who did not seem to have any control over his emotions... It was always a physical gesture, a violent gesture, and always right in the face." Monique's sister confirmed these details to the judge, although Gharbi protested that they were not true. Nevertheless, the judge awarded custody to Monique. Still, young Gamil was not free of the man until he was 7 years old, and the exposure for that long to Gharbi's temper and beliefs had a strong influence. The boy so hated him that when he was 13, he changed his name to Marc Lépine.
(Ramsland, 2004)


The hypothesis here is that Gharbi exerted a profound influence on his son’s future psychological development. Some rightwing bloggers go so far as to suggest that Marc Lépine himself became a Muslim, as evidenced by the beard he grew as a young man. This is unlikely for several reasons:

– He was baptized a Roman Catholic and received no religious instruction. His mother describes him as "a confirmed atheist all his life."

– He had no contact with his father past the age of 7.

– At the age of 14, he legally changed his name from Gamil Rodrigue Liass Gharbi to Marc Lépine. This was motivated partly by hatred of his father and partly by a desire to avoid being treated as an Arab at school.

– His suicide note contains no Islamic references. In fact, his use of several Latin expressions (Ad Patres, Casus Belli, Alea Jacta Est) suggests he still felt some connection with Roman Catholicism.

– As for his beard, he grew it to cover up his acne.

O.K., so Marc Lépine was not a crypto-Muslim. But maybe he unconsciously imitated his father’s behavior. We often hear this kind of argument at trials where a violent offender is shown to have had an equally violent father. The offender should thus be judged more leniently, given his poor role-model.

In Marc Lépine’s case, this kind of argument is at the limit of credibility. Remember, Gharbi was a hated parental figure who had left Lépine’s life at the age of 7. More to the point, we see the same psychological similarity between parents and their children even when the children are taken away shortly after birth and put up for adoption:

… compared to genetic children, American adoptees have a higher overall risk of contact with mental health professionals, specifically for eating disorders, learning disabilities, personality disorders and attention deficit hyperactivity disorder … They also have lower achievement and more problems in school, abuse drugs and alcohol more, and fight with or lie to parents more than genetic children …


… Adoptees may be genetically predisposed to negative outcomes at higher rates than the general population. Genetic factors clearly contribute to alcohol and drug addiction, as well as to some mental disorders like attention deficit hyperactivity disorder and schizophrenia …. An association between nonviolent criminality has been found between European adoptees and their genetic parents … Furthermore, research with Swedish adoptees suggests 55-60% of their educational performance is explained by genetic factors, and that the number of years of school adoptees complete is significantly related to how many years their genetic mothers completed
...
(Gibson, 2009).


On the specific issue of male aggressiveness, we see moderate to high heritability when adopted children are compared with their biological parents. A heritability of 40% is suggested by a meta-analysis of 51 twin and adoption studies (Rhee & Waldman, 2002). A later twin study indicates a heritability of 96%, the subjects being 9-10 year-olds from diverse ethnic backgrounds (Baker et al., 2007). This higher figure is due to the closer ages of the subjects and the use of a panel of evaluators to rate each of them. According to the latest twin study, heritability is 40% when the twins have different evaluators and 69% when they have the same evaluator (Barker et al., 2009).

This is not to say that the Montreal massacre was genetically inevitable. If Lépine had found a girlfriend, who would have put up with him, he would have probably become a man like his father but nothing more serious. The tragedy on December 6, 1989 resulted from three interacting factors: 1) a latent predisposition to violence, probably in the form of low thresholds for ideation and expression of violent behavior; 2) lack of close friends, especially female friends; and 3) an enabling ideology.

References

Baker, L.A., K.C. Jacobson, A. Raine, D.I. Lozano, and S. Bezdjian. (2007). Genetic and environmental bases of childhood antisocial behavior: a multi-informant twin study, Journal of Abnormal Psychology, 116, 219-235.

Barker, E.D., H. Larson, E. Viding, B. Maughan, F. Rijsdijk, N. Fontaine, and R. Plomin. (2009). Common genetic but specific environmental influences for aggressive and deceitful behaviors in preadolescent males, Journal of Psychopathology and Behavioral Assessment, early view.

Gibson, K. (2009). Differential parental investment in families with both adopted and genetic children, Evolution and Human Behavior, 30, 184-189.

Lépine, Monique & H. Gagné. (2008). Aftermath, Viking.



Lépine, Marc. (1989). Lettre de Marc Lépine,
http://www.philo5.com/Feminisme-Masculisme/890612%20Lettre%20de%20Marc%20Lepine.htm

Marc Lépine - Wikipedia

Ramsland, K. (2004), Gendercide – The Montreal Massacre.
http://www.trutv.com/library/crime/notorious_murders/mass/marc_lepine/10.html


Report of Coroner’s Investigation http://www.diarmani.com/Montreal_Coroners_Report.pdf

Rhee, S.H., and I.D. Waldman. (2002). Genetic and environmental influences on antisocial behavior: A meta-analysis of twin and adoption studies, Psychological Bulletin, 128, 490-529.