User blog comment:CNBA3/Luffy's Mother Theory!/@comment-3203286-20150326103154/@comment-5303512-20150326105415

Not entirely, it could be a trait passed down from parentage, look at Ace, he had similar traits to Roger, like getting angry to anyone who insults people he cared about. And Ace hated his father.

It can be that children have some similarities to their parents.