(As a triplet i think i should answer this)
Answer:
Twins and people who look the same are not always as similar as you think they are. Though they are mostly they have things like personalities and ways of learning. One thing that's always different no matter what is their finger prints. In any twin study the one thing thats different if their fingers because everyone no matter who they will always have a unique set of marks on their fingers.
Hopefully this helps and good luck.