Sons' intelligence linked to dads' criminal history

Sons whose fathers have criminal records tend to have lower cognitive abilities than men whose dads have no criminal history, according to a new study.
The research, conducted by scientists in Sweden and Finland, found that the link is not directly caused by fathers' behaviour but is instead explained by genetic factors that are shared by father and son.
"The findings are important because cognitive ability is among the most important psychological predictors of many important life outcomes, including socioeconomic success and health," said lead researcher Antti Latvala of the Karolinska Institute in Sweden and the University of Helsinki in Finland.

Latvala and colleagues set out to investigate how parents' antisocial behaviours - such as rule-breaking, aggressive, or violent behaviour - might affect their children's cognitive development.
"We wondered whether children of antisocial parents also have lower cognitive ability than children of non-antisocial parents, and if so, whether compromised cognitive functioning might be part of the inherited risk for antisocial behaviour," said Latvala.
The researchers took advantage of extensive data collected from Swedish residents, including data on cognitive ability acquired as part of compulsory military conscription and data on antisocial behaviour (in this case, defined as criminal convictions) obtained from a national crime register.

Looking at data from over 1,000,000 men, the researchers found that men whose fathers had any criminal convictions tended to have lower cognitive-ability scores than men whose fathers had no such history.

"Perhaps most surprising was the clear gradient seen in the magnitude of the association with sons' cognitive ability by severity of fathers' criminality: The more severe crimes the father had committed, the poorer was the sons' cognitive performance," said Latvala.
The researchers then compared the link between fathers' criminal history and sons' cognitive ability across cousins whose fathers had varying relationships to each other.
They examined the link in cousins whose fathers were half-siblings (sharing about 25 per cent of their genetic makeup), cousins whose fathers were full siblings or fraternal twins (sharing about 50 per cent of their genetic makeup), and cousins whose fathers were identical twins (sharing 100 per cent of their genes).

The data showed that when the researchers took the varying genetic relationships into account, the association between fathers' criminality and sons' cognitive ability gradually diminished.
"Our results thus indicate that despite the adversities related to parental criminality, having a father who has been convicted of crime is unlikely to influence cognitive development in the offspring when the effects of other factors associated with parental antisocial behaviour, including genetic risks, are taken into account," the researchers said.
The study is published in Psychological Science, a journal of the Association for Psychological Science.