On the other hand, you seem to adopt the extreme position that heredity plays NO role.
That is correct. When it come to the human brain and the human heart we are made, first by others and then by ourselves.
The making of ourselves is the biggest part and why you have some children who come out of dire circumstances helpful and gentle people and other children who come out of what should have been happy circumstances nasty and brutal.
Each has chosen to be what he wants to be.
People tend not to like this answer because it puts everything on themselves. However, it is the answer that fits the facts as known today.