Tuesday, May 22, 2012

Identical vs. fraternal... continued

After that last post about Julia and Emma's similarities, I also want to point out how interesting it's been to watch Ada interact with her sisters. She knows who is who, she knows who sleeps in which bed, and which sippy cup belongs to which sister. She gets it right 99% of the time.

But every now and then, they'll all be running around, and she'll lose track of who she thought was where. Then she'll yell at Emma for taking her toy, while it was Julia, or vice versa. Emma usually prefers to sit in the back seat of the van, but the other day, she chose to sit up front with Ada. Ada is obviously used to having Julia next to her. Ada looks at Emma who has fallen asleep next to her, and says, "Julia is sleeping." I say, "Nope, that's Emma who is sleeping!" Poor Ada looks utterly confused and perplexed, and says, "There's so many Emmas!"

Now when we accidentally use the wrong name, we joke that there's so many Julias or Emmas. Please excuse my amusement at Ada's expense - it's just so darn cute.

In our defense, Julia will look at herself in the mirror, and say, "Hello, Emma!" or Emma will look at herself in a picture, and say, "That's Julia." Apparently sometimes they can't tell themselves apart either. When all three appear in a photo, everyone knows who is who. However,when I show them a photo of either Julia or Emma, all three of them will get it wrong 50% of the time. So clearly they're just guessing and don't really know.

I find all of this completely fascinating, because even if they're proven to be all fraternal, I do think Julia and Emma share a lot of the same DNA. My guess is that they could be mirror identicals, based on their opposite handedness and opposite hair swirls. Interestingly, their hemiparesis diagnoses is also opposite. Ons has a mild left hemi diagnosis and the other a mild right hemi diagnosis.

I've read that the gene expression can be about 5% different in identicals, and I'm always wondering if that is what accounts for their differences. I realize nurture and epigenetics play a role too. Although, given that they've been in the same environment since conception, I do not know how much weight to place on nurture being responsible for differences.

There are several factors that increase the likelihood of having identals. Not only were my eggs older when we completed our 2nd fresh IVF cycle, but we also had to do intracytoplasmic sperm injection (ICSI).

Interestingly, I also have two sets of twin cousins on my mother's side of our family, but it never crossed my mind that we could become parents to multiples. We were just trying so hard to conceive, that having multiples seemed like an impossibility. Having Higher Order Multiples seemed utterly farfetched.

We definitely hit the baby jackpot, but if it turns out that Julia and Emma are identical, I think it will just underscore how incredibly fortunate we were to have had these three amazing kids at all.

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