Conservative Bias Revealed

There is a study out that is stirring up quite some debate in the blogosphere. At the one hand it shows that adopted children do not tend to inherit their parents social well-being in terms of family income, as do biological children. At the other hand, it claims to show that drinking and smoking habits are transmitted from parents to children irrespectively of the parenthood is biological or through adoption:

"transmission of drinking and smoking behavior from parents to children is as strong for adoptees as for non-adoptees. For height, obesity, and income, transmission coefficients are significantly higher for non-adoptees than for adoptees."

Alex Tabarrok quickly rushes out to display his conservative bias by solely focusing on the parts of the results that might be used for underlining the importance of our genes:

"What do parents transmit to their biological children but not to their adopted children? Genes. When we observe, as we do, that low-income parents tend to have low-income children and high-income parents tend to have high-income children we should not bemoan the inequities of nurture but rather the inequities of nature."

Alex says absolutely nothing about the part of the results that severely undermines our belief in the relative importance of the genes. That's bias. A conservative bias to comfort those who feel threatened by the social mobility of the dynamic modern market-economies. Let me try a more down-to-earth analysis:

If you are adopted from Korea to the U.S., you are likely to eventually get an income well below that of your new parents, the study says (but probably far above that of your biological parents I guess). Probably, in my opinion, because you are likely to have got a far worse start when it comes to such things as nutrition, breast-feeding and suffering the trauma of separation from your biological parents. Having a different-colored skin is another thing that might cause problems (signaling to counterparties facing adverse selection), so its no wonder your average expected family income is lower than that of your new parents. What about the broken link between the parents' and the children's present and future family income? Its broken, says the study. But it does not say whether its broken because the lack of genetic linkage, or because of the adoptees' adverse experience in early childhood. And in any case, the results on drinking and smoking clearly shows that we often tend to believe too much in the importance of genetic links.

Continuing the analysis from the perspective of the adoptee also reveals the cruelty that lies just one step ahead in the direction of Alex' analysis. Being forced to leave one's children has after all to be viewed as some kind lack of economic success. And if economic success is in the genes, adoptees have not tended to inherit much on it. Weak genes and hardships in early childhood. That's just too much. I don't want to believe it. And I don't do believe it. But I still try to keep up some unbiasedness when thinking about it.