There's the structure, but so much of what we recognize is also the details of the expressions. I have an aunt who was adopted at 7 and she said all her life people could not believe she was adopted. This was a time when they made a big effort to "match" looks, but I think what really made people think she must be genetically related was that she and her parents shared these micro facial expressions and posture and mannerisms that they just subconsciously learned from each other.