Posted by: michelleann | February 15, 2010

Interesting

  • A set of boy/girl twins can only be fraternal (dizygotic). Boy/girl twins can not be identical (monozygotic).

Except….

However, there have been a few reported cases of a genetic mutation in monozygotic male twins. For some reason, after the zygote splits, one twin loses a Y chromosome and develops as a female. The female twin would be afflicted with Turner Syndrome, characterized by short stature and lack of ovarian development. It’s extremely rare; less than ten cases have been confirmed. Given the odds, it’s safe to assume that 99.9% of all boy/girl twins are fraternal.

Okay, One More Exception…

Of course, another explanation for gender differences in identical twins is an identical twin who undergoes a sex change operation.

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Responses

  1. I love the title of your blog, and this interesting blog post. My name is Abigail Pogrebin; I’m an identical twin and former 60 Minutes producer who just published a book about twins called “One and the Same.” I think any parent of twins will find much to chew on and maybe some guidance as to how to dodge pitfalls of doubleness. I’d love to speak to you about the possibility of a book giveaway, review and/or author Q&A. My email is apogrebin@gmail.com, website:www.abigailpogrebin.com.


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