Good and evil can be defined from a non-religious standpoint, altruism and sadism exist in the world even if God doesn't and by common secular definition most people would call the 1st good and the latter evil. Even if you want to argue that its all operant conditioning, at the end of the day the result is still individuals that exhibit behaviors that will be judged as good and bad by the general culture. I grant "evil" does carry more religious semantic baggage than "bad", but practically speaking I don't know how much difference that word choice makes to how people evaluate the actions of others.
Stepping back, It's attractive but in the end difficult to assign environmental blame for every screwed up person. Trump's older sister was a respected Federal Judge. It's true even siblings in the same home do not have the same experiences, but if the same parent has to be defined as a good parent to one child and a bad one to another in so many cases you're almost left with the outcome being randomly determined, which practically speaking is indistinguishable from saying the personality outcome was latent in the individual maybe subject to some combination of particular environmental triggers - which sounds close to how you frame it above. And absolutely everything we know about genetics and the brain argues there must some spectrum of genetic traits that affect personality but as a culture we still hold each person responsible for themselves in all cases short of a diagnosis of clinical incapacity. We don't have much choice because law as the organizing principle of society collapses if we ever accept a general proposition that people cannot overcome the environment they developed in, even if we sort of nod to the idea informally.