Book title needed

Hi! In a thread a couple of months (genetics vs upbringing) back, someone here mentionned that he saw a tv show (pbs or similar) on a university professor (big institution, Harvard?) who did a study to find out how much one`s personality was genetically programmed, with enough juice to write a book about it. That person had not read the book but gave me a link to a page that described it well.

If anyone knows what I am talking about, I would really appreciate to have the title. Thanks in advance!