Genetically Informed Study Shows Early Motherhood Is Linked To Offspring Delinquency, But Doesn’t Cause It
A new study suggests that previous research has overestimated the impact of young motherhood on criminal and antisocial behavior in offspring. The study, published in Psychiatric researchfound that the relationship between maternal age at birth and offspring adolescent delinquency disappeared after controlling for demographic and family variables.
“My research focuses on intergenerational influences on criminal behavior because parents are thought to have a significant influence on their children’s behavior, including antisocial or criminal behavior,” the study author said. Steve van de Weijersenior researcher at the Netherlands Institute for the Study of Crime and Law Enforcement.
“Previous studies have consistently shown that young motherhood is a risk factor for problematic behavior in their offspring. However, it was less clear to what extent this reflects a causal effect or whether this link is the consequence of other factors driving both to early motherhood and offspring delinquency.
For his study, Van de Weijer analyzed data from the registers of Statistics Netherlands, a government agency responsible for providing data on all Dutch citizens from several official sources. In addition to police data, the agency collects various demographic and socioeconomic information, such as household income, education level, employment status, and maternal and paternal death.
The sample comprised 2,098,815 people born in the Netherlands between 1991 and 2001. About 11% of the sample committed offenses as teenagers.
Van de Weijer found that people whose mothers were younger were more likely to have been suspected of at least one crime between the ages of 12 and 18. But the relationship between mother’s age at birth and adolescent delinquency was no longer statistically significant for the control variables.
“Children in the Netherlands are more likely to be involved in criminal behavior during adolescence if they have a younger mother: a one-year increase in mother’s age at birth is associated with a 6.4% decrease in offspring’s risk of delinquency,” van de Weijer told PsyPost.
“This association disappears, however, after controlling for various demographic and socioeconomic characteristics and after controlling for unmeasured family factors, such as genetics, by comparing cousins of mothers of different ages. This shows that the relationship between early motherhood and offspring adolescent delinquency in this study is a spurious relationship and does not reflect a causal effect.
As with any study, however, the new research includes some caveats.
“This study was based on official registry data, such as police data to measure adolescent delinquency,” van de Weijer explained. “Since the majority of criminal acts are never detected by the police, it is very likely that various members of the sample were considered non-offenders when they might in fact have committed crimes for which they did not have simply never been arrested.”
“In addition, this study is based on data from the Netherlands, where teenage pregnancy rates are relatively low and there is an extensive social protection system. Therefore, the results might not be generalizable to countries in which young mothers are more often adolescents and where there is no extensive social protection system that could mitigate the negative consequences of young motherhood.
Nevertheless, the results highlight the importance of genetically informed research models.
“The results of this study are consistent with a growing body of research that shows that associations between parent and offspring behaviors are attenuated when comparisons are made within families rather than between unrelated individuals,” said van de Weijer told PsyPost. “This illustrates that unmeasured family factors – genetic factors and/or shared environments – explain (in part) intergenerational bonds. It is therefore important that studies use family-based research designs when investigating intergenerational effects, to account for these unmeasured family factors.
The study, “No causal relationship between early motherhood and adolescent delinquency of offspring: empirical evidence from a genetically informed study“, was written by Steve van de Weijer.