Tuesday, March 27, 2007

Fratentical Twins?

In my life, I've only ever personally known two sets of "twins" - my dad and his late bro, and my friends HB and MB. I've long suspected that the labels of either "identical" or "fraternal" did not apply entirely to either set of twins, and perhaps now my suspicions might be confirmed.

According to this article, a new twin variation has been identified, where there is only one egg but two sperm who have managed to penetrate into the egg prior to dividing up into two separate embryos. In the past, they believed there were only two ways to create twins: two separate eggs and sperm (fraternal), and one egg and one sperm that divided into two whole embryos (identical).
Personally, I believe in this semi-identical twin theory. In the case of my dad and late uncle, they looked far too much the same in their early years to be fraternal, and yet they were considered as such. In the case of HB and MB, they looked way too different to be considered identical, and yet the evidence suggests that they are genetically-identical twins.

So now, this proposes a third theory into the mix. However, it may not be a perfect theory in that it has yet to answer how the DNA then matches up; if you're not entirely identical, does that not make you automatically *different* and therefore, essentially fraternal anyway?

I'm no geneticist so this is way beyond my realm of understanding, but it is nice to think that perhaps there is more to my long-existing suspicions than just "gut-feeling." And even if it doesn't lend total support to my personal theory, just let me live in my little bubble anyway, okay?


4 comments:

Natalie said...

That is really interesting. I had never even considered it a possibility but I know what youmean about people looking so almost alike that it had to be a third thing. One of my favorite twinisms is the Chimera, two embryos that fuse into one. One person ends up with two sets of DNA. Some look very strange but others you would never know were Chimeras until their kids are born with DNA that doesn't match their own. Once they tried to take away a woman's children because DNA proved they weren't hers (it was figured out eventually). You would think she would know if she gave birth. Sorry for the long comment. I get excited by science.

With Love, Fat Girl said...

I saw that article too, and shared your opinion on it. So now we have twins that look alike, twins that don't look alike, and twins that don't quite look alike. Bugger. It's a little odd to me.

Catherine_Jane said...

Same parents... same DNA... ten years apart and you'd be troubled to catch the family resemblance... but he is and always will be my brother!

Mrs. Loquacious said...

Natalie - I've never heard of the Chimera...but it sounds oddly fascinating, and rather unfortunate. :S

WLFG - It is odd, isn't it? But then again, everything about the human body is entirely strange to me.

Catherine - True true. But the "same DNA" is not exactly the same in your case, and I'm thinking you two ended up with the most diverse sets available within your parents' genetic make-up. Unfortunately, we can't pick our families and we cannot choose our genes. (Or maybe this is a good thing? I wonder if I could choose, whose genes would I have...and would they work out well together?)