As I said, to a very important extent it is true. Identical twins have a lot more in common than any other two people, even close siblings, often even when they are separated at birth. This gets us into semantics about what "identity" is, but that is indeed the issue that I'm trying to raise anyway.
> Modern twin studies have concluded that almost all traits are partly influenced by genetic differences.
> Modern twin studies have concluded that almost all traits are partly influenced by genetic differences.
https://en.m.wikipedia.org/wiki/Twin_study