Years of anecdotal evidence provided by clients suggested to all of us that parents mattered a great deal. We also knew what parents had said and done to our clients. The connection seemed obvious. In fact, he believed Harris' find would be one of the most important psychological discoveries of our time. This is no surprise to parents who have had more than one child.
Children have a core temperament that appears from birth.
It seems to me one would be constantly paddling upstream, and that more sophisticated measurement might still reveal a closet introvert. In order to answer these questions, I believe we must make a clear distinction between personality and mental health. And here, I think, parents can have a substantial effect. As I have suggested in many essays on this site, parent-child relationships are replete with subtext. This subtext can be facilitating, damaging, or neutral.