I love living in the future.

[theweaselking]

Genes of identical twins not actually 100% identical.

This is super-useful for nailing down things that have a genetic cause: Find twins where one has a condition and one does not, sequence them for the differences. Then check those difference-spots against other people with and without the same condition.

Comments

[ladybird97.livejournal.com]

My stepdad has friends who are identical triplets. Two were diagnosed with Type I diabetes as kids, but the third doesn't have it. They've been the subject of studies for ages :)

(which is not to say that this is old news; just to say, yes, this is totally a thing, and science is awesome.)

[matrixmann]

For multifactorial diseases which have a genetic component, but it doesn't work as directly, the thing had been noticed.
Perhaps you call that "the unidenticalness" of even identical twins, or that's what they always say "life circumstances".