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The Twins That Are Neither Identical nor Fraternal
They shared a placenta, but on the ultrasound, one looked like a boy, and the other a girl.
A few years ago, Michael Gabbett got a call from a very confused ob-gyn. A woman had come in pregnant with twins who should have been identical—they shared a placenta, meaning they must have split from a single fertilized egg. But doctors could also see, as plain as day on the ultrasound, that one looked like a boy, and the other, a girl.
How could the twins be identical but different sexes? “My initial reaction
