Karolinska Institute: New research from Sweden’s Karolinska Institutet in
collaboration with Oxford University shows that close relatives of men
convicted of sexual offences commit similar offences themselves more
frequently than comparison subjects. This is due to genetic factors
rather than shared family environment. The study includes all men
convicted of sex crime in Sweden during 37 years.
“Importantly, this does not imply that
sons or brothers of sex offenders inevitably become offenders too”, says
Niklas Långström, Professor of Psychiatric Epidemiology at Karolinska
Institutet and the study’s lead author. “But although sex crime
convictions are relatively few overall, our study shows that the family
risk increase is substantial. Preventive treatment for families at risk
could possibly reduce the number of future victims.”
The report is published in the
International Journal of Epidemiology
and based on anonymised data from the nationwide Swedish
crime and multigeneration registers.The research included all 21,566 men
convicted for sex offences in Sweden between 1973 and 2009, for example
rape of an adult (6,131 offenders) and child molestation (4,465
offenders).
The researchers looked at the share of sex crimes perpetrated
by fathers and brothers of convicted male sex offenders and compared
this to the proportion among comparison men from the general population
with similar age and family relationships.
The results suggested familial clustering of sex offenders,
about 2.5 percent of brothers or sons of convicted sex crime offenders
are themselves convicted for sex crimes. The equivalent figure for men
in the general population is about 0.5 percent. Using a well-established
statistical calculation model, the researchers also analysed the
importance of genetic and environmental factors for the risk of being
convicted of sexual abuse.
“
We found that
sex crimes mainly depended on genetic factors and
environmental factors that family members do not share with one another,
corresponding to about 40 percent and 58 percent, respectively”, says
Niklas Långström. “Such factors could include emotional lability and
aggression, pro-criminal thinking, deviant sexual preferences and
preoccupation with sex.”
Self-reported sexual victimization rates in Sweden are largely
similar to those in other Western and central European nations, Canada
and the USA. Other cross-national comparisons of police-reported
offences should be done cautiously because of differences in legal
definitions, methods of offence counting and recording, and low and
varying reporting rates of sexual violence to the police.
The research was funded by the Swedish Prison and Probation
Service R&D, the Swedish Research Council, the Wellcome Trust and
the CIHR Banting fellowship program. Niklas Långström is also the
national scientific advisor for the Swedish Prison and Probation
Service.
Open access p
ublication:
‘Sexual offending runs in families: A 37-year nationwide
study’, Niklas Långström, Kelly M. Babchishin, Seena Fazel, Paul
Lichtenstein & Thomas Frisell,
International Journal of Epidemiology
, online 9 April 2015.