It was an axiom in most social sciences that adoption was inevitably traumatic and harmful. When colleagues find out I am adopted, they go all caring and therapeutic and ask me about the birth parents and how horrible it was. They don’t know that my Mum and Dad were fantastic parents (and you were, if you are reading this).

They also don’t understand that the outcomes for adoption, done properly, are often better than if you stayed in the social strata you would have been born into. You still have inherited risks, but the environment can modify things. The paper is looking at full and half siblings when one was adopted out… and their risk of offending. Which, in general, is lower.

The only human trait of which we are aware that has been examined utilising the design we implement here has been IQ. Several prior investigations have shown substantial gains in IQ or improvements in school performance in adopted v. non-adopted siblings. The rearing environment provided by an adoptive family might reduce risk for convictions in many ways.

Adoptive parents are carefully screened in Sweden for their ability to provide a high-quality rearing environment. Because the number of children available for adoption has been considerably smaller than the demand, the selection process is rigorous.
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Many aspects of parental and family functioning assessed in intact families correlate with risk for offspring criminal behaviour including low socioeconomic status, young parental age, parental divorce or death, a parental history of criminal behaviour and/or psychopathology, and disrupted family functioning . We have shown that compared with the biological parents of adoptees, adoptive parents in Sweden have substantially lower rates of many of these risk factors including a history of criminal conviction, drug abuse, psychiatric hospital admission, AUD and divorce, and had higher rates of education and were on average substantially older.

Many of these features in the adoptive parents (including criminal convictions, AUD, drug abuse, divorce and young age) significantly predicted risk for criminal conviction in their adopted child so that we can be sure that their effect was environmentally mediated.

Environment matters. Ordinary parenting, consistent, old-fashioned, stable, boring… helps kids grow up with lower risks than their parental history would suggest is the case. That is good.

However, there is a risk remaining. Because it is not your adoptive parents that give you the genetic risk. That comes from your birth parents.

But those weaknesses can be managed. We do have free will. We can modify the risks that remain. And honouring parents who raise their kids is becoming more important, particularly as most children now come from divided families.