My uncles are identical twins and I can easily distinguish them, even in baby pictures. How can this variation exist?
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Genes are only one component of what makes you look the way you do. Other factors like your environment, diet and lifestyle choices impact your appearance. So, while your genes play a large part, they aren’t the whole story.
> How can we still tell some identical twins apart if they have the same genes and are supposed to look exactly the same?
That is an incorrect assumption.
First, the genes are not necessarily identical because there can be mutations, but that is not why you can tell them apart.
It is “are supposed to look exactly the same?” that is the problem. The genes control how the body grows but do not contain exact information about the body configuration of cells. The body growing induction is more of a recipe and exactly what the result has a small variation.
Look at your own skin, and its exact structure, where you have hair follicles, birth marks etc. It is not uniform pattern, it is create but process with small variations in the result.
So the practically identical genes result in two babies that are quite similar but not identical.
Because people are not entirely defined by their genes–the environment plays a VERY strong role in physical development. Consider the following two cases which can obviously affect differences in appearance:
1) One twin smokes, the other doesn’t
2) One twin has a deficit of of food, while another has a surfeit of food.
I am a monozygotic twin and have great difficulty distinguishing between myself and my brother in old photographs; however, any photo taken after high school or so and I can easily tell (and not just because those were my clothes and the others were my brother’s).
Even when young my parent’s could tell the who was who because there WERE subtle differences. I had much greater difficulty since I was not practiced in seeing both of our faces at the same time. We weren’t frequently looking in mirrors together, and had more “important” things to do than spend hours looking at photographs.
One great example of environmental impact on body features are fingerprints–my brother and I have different fingerprints. Fingerprints are formed during the early development and are caused by touching things inside the womb and creating “friction ridges”. These get set by the time you’re around 6 month old.
We both did one of the genetic ancestry things and we had a 100% DNA match. Our ancestries came out SLIGHTLY different, but that was due to the fact that we were tested using different versions of the company’s genetic identifying IC.
Even if genetically the same, they don’t live the same life… eat differently, exercise differently, sped time differently, learn skills and movement differently, groom differently, dress differently
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