Identical Twins Are Not Truly Identical

[n2doc]

by JOE PALCA

February 18, 2010
How would you find out why identical twins differ slightly from one another? You'd turn, of course, to worms.

At least that's what Arjun Raj did.

He's interested in what factors shape our appearance. It's well-known that as children grow, things like diet and exercise can alter the way they look as adults. But Raj and other molecular biologists suspected something else was going on.

Genetically Identical Worms Are Different

To find that "something else," ideally you want to rear twins under identical conditions in the lab for about 20 years. Since that's never going to happen, Raj turned to a tiny worm called C. elegans.

more:
http://www.npr.org/templates/story/story.php?storyId=123820029

[aquart]

1. Worms? WORMS?

[Lithos]

2. Interesting article

Though there is that pesky "evolution" thing again.

L-

[Kurt_and_Hunter]

3. Interesting, but the premise is off

Of course environment makes identical twins a little different and would make clones a little different also. Is a chemical process of gene expression environment or does the gene have its own phenotype... if gene x may result in RNA z or y or q does that mean the gene is three-way?

Or is the variability of expression an aspect of the environment or the gene?

Given enough weed one could argue either side.

But a gene says "xyz" and that might be expressed in different ways then that's not so different from saying that identical twins raised on different food will be different.

Yes, this gets into tautology... in the way identical twins are identical (genetically) they are in fact identical. So the headline is misleading there. And in the way they vary (the expression of those genes) they differ. But everyone always knew that.

(Thought experiment: Could we intercede to make that RNA expression even more variable? I am guessing we could with some chemical or another. So that would clearly be environmental.)

So the story here is that these worms seem to have have some randomized range of gene expression that results in a proportion of differences in the population of identical worms.

That's quite interesting.

But the headline hook does the interesting part a disservice.

[MineralMan]

4. I dated one of a pair of identical twins for a while.

They weren't absolutely identical, but almost. One (the one I dated) had a tiny mole just below her right ear. One time, they thought they'd play a trick on me. When I went to pick up my girl friend, they pulled a switch on me.

I noticed the missing mole, though. Fun ensued, and fun lessons were learned. I continued to date the one I had started dating though, although they never pulled that trick on me again.

Note: The other sister (the one without the mole) was a better kisser. Good times.

[BadgerKid]

5. +1. n/t