I think that the nature vs. nurture is a question that is as old as time, and wonder if it ever really can be answered.

It seems pretty clear that Fanny's behavior is the result of nature and nurture (and the lack of nurture too).

We were told that Mrs. Norris did help form her nieces minds. With Sir Thomas' sternness, and Lady Bertram's neglect, Mrs. Nasty's tutoring won the day.

As to Sir Thomas, I think he is a very believable character. Stern father figures who don't show a lot of affection, and don't get involved with child rearing are hardly a rarity historically.

Nature has a lot to do with it too. I think for a parent to see and correct a child in selfishness(this novel as example), would require a lot of self knowledge and being observant of the children. I've heard the saying a lot "There should be a license required to have children." A parental figure can encourage or discourage a child's natural tendencies by their actions and example.

I agree that MP doesn't make sense of the nature vs. nurture question, but because it's not an either/or question to be answered.

This thread has been fascinating to read, and the idea makes sense that perhaps Edmund inadvertently got more encouragement from his father because he was naturally like him.