Anecdotally, in my old neighborhood, I knew of three families with a child adopted as an infant from from troubled circumstances. All three were raised together in the same household and with the same parenting as their non-adopted siblings. It’s a wealthy neighborhood, so the biological children ended up as studious, stable, high achievers.

The adopted kids, not so much. One worked at the store where I worked, and got fired eventually, since she was flaky, unable to focus on the job, and solicitous of any and all male attention. She showed up on the front page of local news sites one day because her parents reported her as a missing person. Turns out she went home with a guy she met at a bar and didn’t bother to tell anybody. Her co-workers were not surprised.

Another was my apartment neighbor, who was 19 and dating a 50-something guy. She couldn’t hold down a job, and he supported her. She eventually moved in with him, and told a homeless friend that he could move into the apartment her parents paid for. (He was a lot cleaner than the rabbit she barely cared for.) After she left, the fruit fly infestation in my apartment cleared up, and my landlord threw out the refrigerator from her unit rather than clean the maggots out of it.

The third was the worst. She got involved with a guy, hatched a plan for he and his friend to rob her parents, but the robbery went wrong and they murdered them instead.

The fact that all three turned out the polar opposite of the biological kids in the same environment sure points to some inborn traits.