How to become a good parents

As long as the children are happy then you're going to be okay.

In my opinion, it is almost entirely down to parents. Of course there are other factors involved but most the time, the way the parents deal with the other factors has more of an impact. Some people will give their kids all they can and the kids will still not do well and vice versa. Some kids who have terrible parent smay grow up to reaslise they want to be better than that so yes, it's still mostly about how they are raised. If you are raised well, then you (in most cases) will grow up well.