We’re getting the twins DNA tested. Not to establish paternity – Charlotte’s general build and ability to burp after only a sip of milk leaves that in little doubt – but instead whether they are identical twins.
You might reasonably wonder, can’t you just tell by looking at them? Not quite, because the difference in weight (though Romilly is doing splendidly at closing the gap) shows in their faces, and it’s therefore always easy to tell them apart when they’re side by side. But on their own sometimes even I – their own mother, the shame! – have to check their ears (though Romilly’s ‘frilly bit’ is growing out) and their stork marks. Jon disagrees (which is odd, given the amount of times he’s got them mixed up!) but I am prepared to bet money on it or even taking over his turn to do the 2.30am feed. I’ll regret saying that, won’t I…
Normally it’s obvious during pregnancy as identical twins, 99% of the time, are monochorionic, which means they share one outer membrane or sac in the womb. Fraternal twins in contrast have their own little bag of fluid. But in 1% of cases, identical twins still end up dichorionic, and given our track record with odds, the improbable is distinctly probable.
To continue the biology lesson… Fraternal (or dizygotic, meaning two eggs) twins are the result of two sperm fertilising two separate eggs. Effectively they’re just siblings who happen to have flatshared for nine months. They could actually be from two separate moments of conception – which therefore leads to the occasional example of ‘twins’ having different fathers, if the moments of procreation were close enough. Now THAT would make for a gripping episode of Jerry Springer.
Identical (or monozygotic) twins occur when one sperm fertilises one egg, but it splits. If it splits very late, and only in part, that leads to Siamese twins. But if it splits very early, twins with the same DNA end up in different sacs. And that’s what I think happened.
Herewith a diagram in case none of that makes sense!
Why does it matter? In no particular order:
- I just want to know, out of pure curiosity. Given every single part of them is measured and tested I don’t see why this can’t be (Kings wouldn’t), especially given it’s the question every old lady in the street asks us!
- They’ll want to know. That their sister is, quite literally, their other half. It’s very special.
- From a social perspective, it would also be helpful. If they are identical, then it’s all the more reason as we rear them that they’re treated as individuals – by us, their teachers etc.
- Medically, presumably it helps to know, if they’re ever in need, that there is an exact match out there?
And finally, it means they can benefit from the infamous case-collapsing Twin Defence when it comes to the Law. It weren’t me, Inspectah, must ‘av bin me sister.
Not that I am imagining a life of crime for the little darlings, unless it’s on high rolling tables in Monaco where beating the casino involves some Hustler-esque DNA heist, not to mention excellent dresses.
I will keep you posted!
Incidentally, if other twin parents want to find out, some hospitals offer it, often with a lab fee. The reason you have to pay is that they’re not that interested post pregnancy. Identical twins matter to hospitals IF they are monochorionic as then there is the risk of Twin to Twin Transfusion Syndrome (basically when one twins hogs all the food and possibly starts actively taking some from the other); they’re less concerned about afterwards.
We are therefore organising ours through the Multiple Births Foundation, a charity which is also a very useful source of information on all things twinny. Ironically, they use the lab at King’s. Hey ho!