I've found that in a lot of cases, the outcome for a kid is very predictable from the family dynamic early on.
When I see a parent say "No," to their 2 year old, but give in after the kid cries, I promise you they will have a spoiled, unpleasant 9 year old, and an incorrigible 14 year old.
When I see a parent cater to their 6 year old, waiting on him/her hand and foot, never showing the kid how to set the table, do his/her own homework, or hang up his/her own clothes, I promise you they will have a very demanding teenager--and a very incapable adult.
Obviously, innate temperament accounts for something. But I've seen these patterns over and over again.
I have 2 teenagers. They are both good students, athletes, and very decent human beings. I never lifted a hand to them, but there was always a consequence to their actions--good or bad--No meant No, and responsibility meant more freedom. If you apply that principle when they're 3, you don't have to be a strict disciplinarian when they're 13.