Interesting question. I don’t see how you could say that parents don’t make a difference. The question is what is the base line? Better parents will deal with whatever child they are given better. If the child has ADHD, the better parent will handle it more effectively than the worse parent.
The question becomes: can you look at a child and say whether the parents are good or bad without knowing what challenges the child presents? Clearly not. There are children that will be difficult and that will behave in challenging ways no matter how good a parent you might be.
But let’s look at a child that everyone says is a model child. What if that child has a sibling who is also a model? Can we say the child’s parent is an excellent parent just because the kids are such model children? Would you say that the child was always good? Born that way?
Probably not. Children don’t know anything when born. However they behave, a lot of that has to do with what their parents have taught them. I child that behaves well has to have been taught well and raised well. That doesn’t come from nowhere. The parents have to accept the responsibility for that training.
But we still don’t know the baseline. Do we have an autistic child who behaves well? Wouldn’t that be a sign of extraordinary parenting?
And what about children who don’t behave well and who have no illnesses. What if they live in poverty and aren’t raised to value education because their parents don’t have any education? What do we say about the parents? Are they bad parents?
I guess compared to good ones, they are. But perhaps they can be excused for being poor and uneducated. Then again, perhaps there are poor and uneducated parents who do a good job. But then, are they really uneducated if they do a good job? Perhaps these are terms that define each other. It’s a tautology of sorts.
In the end, I think you can’t say for sure what role the parents have played until you have a greater understanding of family life. You need to see the relationships in action. You also need to know what challenges the child faces. Then, I think, if you have all that information, you might be in a position to judge. Not that lack of information ever stopped anyone from judging, anyway.
So it goes.