Sunday, February 20, 2011

Twin Things: Are they identical?

Q: "Are they identical?"

A:  Ok, I get it.  It's hard to tell sometimes.  I've even asked this question of other twins myself.  But my girls don't even look like sisters, let alone twins.  In order to have identical twins you have to have one fertilized egg that splits into two embryos.  When this happens the DNA from the first egg is exactly copied to the second egg, thus creating an "identical" copy.  Here's where it gets tricky.  When this happens early enough in the process, you can have two identical embryos in two separate sacks with two separate placentas.  When viewed on Ultrasound they can appear to be fraternal.  Wow.  And the answer is no.  They are not identical.   They are fraternal twins.  Which means that two eggs (for whatever reason) decided they both needed to go to the party and both met guys and well, you know.

So, science determines whether or not a set of twins is identical.  Not the fact that both of them are girls.  Not even if they are dressed exactly alike.  Not if I cut their hair the same.  It's also not because they were born at exactly the same time.  And it wouldn't have mattered if we would have named them similar or rhyming names either.





Picture 'rights...top: Target, middle: me, bottom: our favorite nanny, Ashli.

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