Sex offending runs within families
We (Långström, Babchishin, Fazel, Lichtenstein, & Frisell, 2015) have recently published a large population-based study and found that sex offending runs within families. Based on all men convicted of any sexual offence (N = 21,566) in Sweden from 1973 to 2009, we found that brothers of men convicted of sex offences were five times more likely to commit the same types of crimes than population controls and that sons of men convicted of sex offences were four times more likely.
What can explain the clustering of sexual offending within families? We found that genetic factors were largely responsible for the effect (40%) and that shared environmental factors, such as brothers learning from one another, had only a minor influence (2%). The genetic effects also tended to be stronger for sexual offences against children than for sexual offences against adults.
“We found that genetic factors were largely responsible for the effect (40%) and that shared environmental factors, such as brothers learning from one another, had only a minor influence (2%) (Långström, Babchishin, Fazel, Lichtenstein, & Frisell, 2015).”
To further examine the genetic vs. environment influence, we compared maternal half-brothers (brothers who typically live together in the same home) and paternal half-brothers (brothers who typically live in different homes). We found that both groups were about twice as likely to offend if their half-sibling were convicted of a sexual offence. If shared environmental factors were largely responsible for the clustering, we would expect a higher risk in maternal half-brothers than paternal half-brothers because they have the same amount of shared genetics but have more shared environmental influence (given they live together). In short, genetics is important when explain why sexual offending runs within families.
One important qualifier: our findings do not imply that sons or brothers of sex offenders will inevitably become sex offenders. The sexual offending rate of population controls (those without brothers or fathers convicted of sex offences) was 0.5% whereas those with a brothers or fathers convicted of sex offences were 2.5%. Instead, our study highlighted that family risk is an important explanatory factor for sexual offending.
“Our findings do not imply that sons or brothers of sex offenders will inevitably become sex offenders.”
Similar to studies that found that genetics influence sexuality in general (for example, sexual orientation and sexual dysfunctions), we found evidence that genetics influence sexual offending. What does this mean? Carefully targeted interventions for families in which fathers or brothers have been convicted of a sex offence may have an effect for reducing sexual offences from occurring in the first place (primary prevention).
“Importantly, this study should not be used to ostracize [this] group… Instead, it should be used to motivate further research on factors that contribute to the risk of sexual offending.”
This clearly would require a lot of forethought (and research on what exactly to target).The next step involves increasing our understanding of the factors (such as birth factors, early childhood factors, parental factors) that could contribute to the risk of sexual offending. Importantly, this study should not be used to ostracize a group that has a 2.5% chance of committing a sex offence. Instead, it should be used to motivate further research on factors that contribute to the risk of sexual offending.
The article is available for free here.
Babchishin, K. (2015, April 9). Sex offending runs within families [Weblog post]. Retrieved from http://wp.me/p2RS15-9E.
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