I've generally been in favor of the nature via nurture idea. I think we all come with the capability to be a lot of things but unless a certain thing is nurtured in time it's not going to happen. I was actually just reading a part in this book I've been slowly getting through talking about the social skills of Romanian orphans from the 90's. Many of these babies interacted very little with adults if at all and the conditions where not good. They studied them throughout their lives after they were adopted and found that babies who where under 6 months when taken from the orphanages grew up to be very similar to regular kids. However the babies who were over that age when adopted had a more difficult time with social interactions and relationships as they aged. I'll check the sources in the book if that stuff interests you.