One needs to distinguish between individuation and genetics. I was researching the dark triad (narcissism, machiavellianism & psychopathy) some time ago and it seems clear that a component of those personality traits is hereditary. It is the same with the big five personality traits (ranging I think from about 40% - 60% inherited genetically).
I think some children might have a genetic predisposition to become bad adults no matter what you do.
I have a theory that dark triad traits have actually been accentuated in certain family lines due to selection.
We know that violent behaviour and addiction are clearly hereditary. So I'd expect some other things would be too. But that shouldn't be a call to start testing parents for the right genes. Or even putting some newborns in special education programs, cause it's a stat. And some seem to avoid the bad stats completely, while some others show the same behaviour without the genes.
There still is freedom of choice...