I would agree that although DNA may offer some small contribution to our personalities, environment and other external factors truly shape who we are. Even though my interaction with my aunts were limited when I was younger and now I don't speak to them much at all anymore, I do have characteristics in common with them. As a child we are constantly absorbing so much information, I would think it's impossible to not think even the smallest of interaction would influence our personalities. I don't know anyone who has been adopted, but I wonder if being adopted at birth, would a child act like their biological parents in any way? Is there evidence of that?
I think the best study to look at regarding biology and adoption are twin studies. These studies used fraternal twins separated at birth and raised in two very different environments, later met as adults, and discovered, they had very similar interests, their intelligence ...
The expert discusses how DNA contributes to personality, as well as environment and external factors can shape our individuality.