Friday, October 24, 2008

So what do we call them now?

Apparently those folks who insist that Matthew and Jonathan are not identical might just be right.
Maybe not now.
But they might be right someday.
Scientists have known for years that identical twins can differ in their expression of genes due to environmental influences, such as diet. But it was always assumed that the basic DNA--the genetic framework--was precisely the same.
A recent study of 19 sets of adult identical twins has throw them for a loop.
The study, conducted by geneticist Carl Bruder of the University of Alabama, found slight differences in DNA sequences in some sets. In one set of identicals in Bruder's study, a genetic variation indicated the risk of leukemia in one twin. That particular twin did, indeed, suffer from the disease.
You see, all of us are supposed to inherit a copy of each gene from each parent, but sometimes, something happens that causes us to have too many or too few. Scientists believe those variations might put us at risk for certain diseases such as AIDS, leukemia, autism or lupus. These differences are called copy number variations and they were just discovered a few years ago.
Previously, the assumption was that if any of these variations were found in one identical twin, they would be found in the other because the twins come from the same egg and share exactly the same DNA.
This study throws that theory out the window.
What remains a mystery, however, is whether these variations occur in utero or as we age. Bruder suspects they come with age. Regardless, his findings mean studies of identical twins could be valuable in figuring out which genes are linked with certain diseases.
But the study raises an even more pressing question: if identicals are not truly identical, what do we call them now? Almost identical? Mostly identical? Sort of identical? Same-egg children?
Will I someday have to admit that those annoying people who stop me in the mall for the sole purpose of informing me that my twins are not identical simply because one has less fat in his cheeks are right?
The implications are frightening.

3 comments:

Lexi said...

i read somewhere that most doctors prefer to call them monozygote as opposed to identical for that reason. They aren't always "identical".

There's Only One In There, Right? said...

Great post.

Here's a few more name suggestions...
One egg babies
Hatched from one egg babes
Semi-Identical
Close enough to being identical

And my favorite....
One Ovum Offsprings

twinsmom said...

People sometimes tell me that my boys are "very identical." I never understood that until I met a pair of identical twins who had notably different birth weights. There are plenty of environmental influences both in utero and after birth that can identicals different.
Great names, There's only one in there, right? I hope you are feeling well. Not too much longer!
Lori