A person is formed through the interaction of their in-born traits with their environment. Different scholars feel that one or the other of these is more important.
It seems clear that there are certain aspects of who we are that we are born with. Some people, for example, seem to be more creative or more solitary from as soon as they are able to display personality. These seem to be innate because they can have siblings who are very different from them even though they are raised in a similar environment.
However, these innate traits do not do all the work of forming us. Instead, we are also socialized by our environment. Our parents and later our friends and teachers convey to us what sorts of behaviors and attitudes are expected of us. Our families can also help to form our abilities (for example, by pushing us to read or to play sports) and our interests (if, for example, we are encouraged to come help at the family business).
In these ways our genes and our social environment interact to form us.