I was looking a homework to do in italki, when I found an interesting question about the personality a few weeks ago. Sadly I can't find it right now, but I think that there it said something like "Do you think the personality is already encoded in the brain or makes while we grow up?". It's curious as I'd already read about that topic before, and I could say the half of the personality is already encoded by the genetic, and the other half is developed through breeding and experience, that's why the personality can change with the time.