Genetic thresholds


Jason Collins


June 23, 2011

In yesterday’s post on crime, I quoted David Eagleman’s statement that “we may someday find that many types of bad behaviour have a basic biological explanation—as has happened with schizophrenia, epilepsy, depression, and mania.” What we now consider culpable behaviour may fall into the class of mental illness, with the criminal justice system adjusting its threshold so.

This threshold issue extends beyond crime. Take IQ, which is highly heritable and correlates with income and most other life outcomes. Where one sits on the IQ bell curve is largely determined by genes. If one’s IQ falls below a certain level, they may receive special schooling, social security and other forms of special care. As is the case for criminal culpability, a threshold is set which considers biological factors.

In each case, is may be worse for someone to be just above the threshold than just below it. It is the person that has a strong genetic disposition to commit crimes, but not strong enough for the justice system to consider it a mental illness, that is the most likely to end up behind bars. Similarly, it is the person with the very low IQ, but not low enough IQ to be considered disabled, that may have the worst life outcomes. The pay-out from the genetic lottery is not monotonic.