Men are up to five times more likely to commit a sex crime than the average male if they have a brother or father who has also been convicted of a serious sexual offence, the largest study of its kind has shown.

A survey of 21,566 men convicted of rape and other sexual crimes in Sweden between 1973 and 2009 has revealed a strong genetic component to sex offending which appears to play a significant influence on the risk of close male relatives going on to commit a sex crime, researchers said.

The study found that about 2.5 per cent of the brothers or fathers of criminals convicted of sexual crimes are themselves convicted of similar crimes–compared to 0.5 per cent of the general male population who become convicted sex offenders.

Scientists said the findings should not be used to excuse sex offending, to restrict the freedom of the male relatives of sex offenders, or to suggest that there are genes for rape or paedophilia. However, they believe the results could lead to better prevention strategies for the sons or brothers of known sex offenders.

“If interventions can be provided that are not harmful, this is an opportunity . . . . We’re not saying you should lock up the brothers of sex offenders, because there is a very small proportion of brothers who go on to offend,” said Seena Fazel, professor of forensic psychiatry at Oxford University.

“We are definitely not saying that we have found a gene for sexual offending or anything of that kind. What we have found is high quality evidence from a large population study that genetic factors have a substantial influence on an increased risk of being convicted of sexual offences,” Professor Fazel said.

“It tells us something about why if we take two sets of brothers whose backgrounds look identical [and] one set has a higher risk of sexual offending than the other, a large proportion of this difference is likely to be due to genetic factors,” he said.

Future studies may discover the genes that influence the risk of sexual offending, and if they do it is likely that these genes are “mediators” of aberrant behaviour rather than contributing directly to the cause of offending, Professor Fazel explained.

The study was possible because of the detailed registers kept in Sweden on convicted sex offenders and their relatives. The scientists looked at offending in the sons, brothers, half-brothers and cousins of men who had been convicted of any sexual crime over the 37-year period, including adult rape and child molestation.

By comparing fathers with sons, and full brothers with paternal half-brothers, who are usually reared in separate families by two different mothers, and maternal half-brothers, who are normally brought up together by the same mother, the scientists were able to tease out the relative influence of shared environment and shared genes on the risk of sexual offending.

This suggested that about 40 per cent of the difference in risk seen between brothers and fathers of convicted sexual offenders and brothers and fathers of those without a similar conviction is due to genetic factors. In other words the heritability is 40 per cent while the rest of the risk is due to shared environmental factors, which can include anything from medical complications during birth and child sexual abuse, to upbringing and family background.

“Importantly, this does not imply that sons or brothers of sex offenders inevitably become offenders too…Just because something is genetically determined, it does not mean that we cannot use the environment to change it,” said Niklas Langstrom, professor of psychiatric epidemiology at the Karolinska Institute in Stockholm and lead author of the study published in the International Journal of Epidemiology.

“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,” Professor Langstrom said.

Rajan Darjee, a consultant forensic pathologist in Edinburgh, who was not involved in the study, said that it is interesting but not surprising to find a strong genetic component to sexual offending.

“Genes influence brain development, and brain functioning underpins psychological functioning, so it should not be surprising to find that genetic factors play a role in sexual offending,” Mr Darjee said.

“The fact that genes play such a role does not mean that a person is less responsible for their offending of that offending is inevitable in someone at higher genetic risk, it just emphasises that genes are an important part of a complicated jigsaw,” he said.

“We should not interpret the findings of this study to indicate that any male relative of a sexual offender is going to commit a sexual offence so they should be put under special restrictions. We cannot know who will or will not commit sexual offences in this way,” Mr Darjee added.

The researchers accept that a major limitation of their study is that it only focused on men who were convicted of sexual crimes and ignored the estimated 80 per cent of sexually abusive acts that are never reported to the police, or the offences that did not result in successful prosecutions.

However, one of the strengths of the study is that it represented the more severe end of the sexual offending spectrum and did not have to rely on the inherent bias of self-reported cases of sexual abuse, the scientists said.

Violent crime in the genes?

The suggestion that sexual offending has a strong genetic component is broadly in line with other research indicating a similar inherited link with violent crime. Although researchers do not suggest there are “genes for rape”, there is some evidence that certain, defined genetic traits may be linked to extreme violent behaviour.

Last year, researchers in Finland suggested that between 5 and 10 per cent of severe violent crime in that country could be attributable to two genes, each of which can modify the activity of the brain in different ways.

However, the important point was that many people carry these gene variants and are not violent. You may inherit a genetic predisposition, but it is possible to control its influence.

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  • Oil Can Harry

    Scientists : “Our studies find a link between genes and criminality.”

    Media: “Stop the presses! This is big news.”

    Scientists : “We’re also finding a link between genes, crime and race.”

    Media: “Oy vey, SHUT IT DOWN! Stop the hate!”

    • Reynardine

      Beautiful strategic use of “oy vey.” You have my upvote, sir.

      • Alexandra1973

        Actually “Mother of God” would likely be uttered by the puppeteers.

        • Reynardine

          Are you trying to blame catholics? Catholics are the least of our problems… maybe except for on immigration.

          • Alden

            Alexandra thinks that the Vatican controls everything Jews have done since 325 AD, communism
            Vulgar movies
            Elena Kagan Ruth Ginsburg Foxman the ACLU SPLC ob and on, the Vatican created Lenin Hitler Trotsky and Stalin the civil war, The world wars
            everything bad that has occurred in the last 1,700 years was done in the home of satan, the Vatican

    • Fr. John+

      This is far more true, and far more believable, than the supposed ‘gay’ gene!
      Bravo. And for the Y-I-D ism, also. John 8:44

    • GrahamSeibert

      Blacks make up about 1.5% of the Swedish population. As elsewhere in Europe, they commit rapes far out of proportion to their numbers.

      The fathers and brothers in this study are of course related by race. They may have left the most critical variable out of the regression.

  • superlloyd

    ”What we have found is high quality evidence from a large population study that genetic factors have a substantial influence on an increased risk of being convicted of sexual offences,” Have they studied blacks and compared them to all others? Probably not, for fear of offending the bantus but we all know what the results would indicate. They’re just like us!!

  • Cheri Rodriguez

    Emmett Till was fast on his way to being Louis Till. The apple doesn’t fall far from the tree.

    • Alexandra1973

      I can only imagine what he would have done, had he not been killed. Suffice it to say he wouldn’t have been a rocket scientist.

  • Whitetrashgang

    You mean one breed of dog is different than other breeds perhaps?

    • Reynardine

      What I have noticed as a brewer is that, while most of my yeast are technically the same species (i.e. Saccharomyces cerevisiae), the variety (race) of yeast matters immensely to the point of selecting one over another can make or ruin a batch of beer, wine, or cider.

      Why do people insist that it isn’t the same with people and the civilizations they make?

      • Earl P. Holt III

        Maybe because “Africanus Criminalis” is lower on the phylogenetic scale than yeast? (Just surmising…)

    • Who Me?

      But… but… but… I could just SWEAR that my corgi is EXACTLY the same as my daughter’s black lab… they’re BOTH dogs after all.

    • Earl P. Holt III

      The black breeds are the most vicious and least trainable…

  • Sissy White

    I wish I could track the article, but many years ago (may have been the Washington Pest) there was an article, that a study was done of women who were impregnated by a rapist and had the child. About 40% of the males by age 25 had been arrested for rape (the other 60% not caught yet?)

    • Alden

      That is why the Scandinavian countries and some of the German states surgically castrated rapists in the late 19th and early 20th centuries

    • Earl P. Holt III

      Did they control for race of the rapist?

  • All of this body of research about genes implies that blacks and other violent groups (Mexicans and Middle Easterners) cannot be cured of their violence by government anti-poverty programs. Thus, I think the race mixing agenda hopes to mix some of those gentle white genes into these groups in hopes that the bad genes go dormant.

    Philip Chism, the mulatto who raped and murdered Colleen Ritzer, suggests that for mixed race males, the bad genes dominate. Chism may have a white mother, but he’s still black in his mind and behavior. So are most of the others.

    • JohnEngelman

      The only way to reduce the crime rate is to get criminals off the street and out of the gene pool.

      • Reynardine

        Only if you also restrict conjugal visitation or sterilize them.

  • JohnEngelman

    This article dances back and forth between saying “Genes are responsible,” and “Genes are not responsible.”

    It is still necessary for criminologists and geneticists to cover themselves against the career stopping accusation of being a genetic determinist.

    Nevertheless, I am confident that in the fairly near future genes will be discovered for various criminal inclinations. It will be possible to predict within a high degree of accuracy which infants will become criminals, and which will not be.

    • LHathaway

      The heritability is listed at 40% (if you can believe them – I don’t believe anything they say). What I got out of it is that if you are being you’re being raised by an anti-social numbskull and/or pervert, there’s a greater chance you will be also.

      • Alden

        In that study mentioned by the Wash Post rapists were raised by their Mothers
        The ones raised by their Mothers and often by the Mother’s family were usually the sons of religious Mothers who didn’t believe in abortion and “it isn’t the baby’s fault”
        Before legal abortion the ones not raised by the Mothers were put up for adoption
        That’s a scary thought

    • expitch

      Than what should be done to or with the infants. By whom?

  • Luca

    Genetics and environment have a synergistic effect. You can argue about the percentages all day long. If the genetics are present and/or the environment play some role, you can pretty well count on a percentage of the offspring following whichever input they received.

  • Simonetta

    Well this study was done in Sweden. The sex laws there are different from any other civilized country. Imagine the most wacko women’s studies professor being allowed to just dictate her most paranoid anti-male fantasies into sex-crime laws that apply to every man in every circumstance. For instance every male:female copulation is considered a legal rape if the male was not wearing a condom. And the female can swear charges against the male years after that copulation on “he said:she said” testimony alone. The male has his passport confiscated and employers/landlord/family notified by the police. And they wonder why their birthrate is so low.

    To compensate for the low birthrate they are importing Muslims by the millions. These men think all Swedish women are free whores provided for them. The Muslim men in Sweden are responsible for almost all of the real rape. No Muslim man will testify against another while the court system in drowning in pseudo-rape (normal courtship behaviors) charges, making it nearly impossible to bring Muslim rapists to justice.

    • LHathaway

      There was an article on the web, MSN or Yahoo entitled woman ‘raped’. The whole article called it rape. What happened is that one female police officer searched another female. This was labelled ‘rape’. If this is evidence of a ‘rape culture’ I don’t know. This also goes for the 30,000 White women raped by black men each year. Many of these are likely inappropriate behavior and assaults labelled ‘rape’

      • Who Me?

        I don’t have any information about the situation you described, between a female suspect and a female officer, but I DO know for a fact that a woman can be (and some have been) raped by a female of the lesbian persuasion.

      • Alden

        The statistics about rape are done by police departments and the DOJ They are

    • Alden

      Back before the sexual revolution Swedish women had a reputation all over Europe for being sexually available

    • WhiteGuyInJapan

      “And they wonder why their birthrate is so low.”
      The birthrates in the Scandinavian countries are in the 1.8-1.9/per couple range-close to replacement. It’s countries like Spain and Italy that have very low birthrates-in the 1.1-1.2 range. Strange, Catholic countries. What are they doing? Or not doing, as the case may be?

      • Alden

        Don’t the Scandinavian birth rates include millions if Arabs and Africans

  • Hilis Hatki

    We can see and indentify genes yet can’t see race and nationality. A buffet ?

  • InAFreeCountry

    “We didn’t find a rape gene, but we found a gene that would make one more predisposed to raping.”

  • Hilis Hatki

    So a propensity to commit rape is in the jeans?

  • rentslave

    Emmett Till Sr.and Jr.

  • John Smith

    It would be interesting to see if maternal half-brothers were less likely to commit rape than paternal half-brothers, indicating some of the genes involved are Y-linked

  • ekwaykway

    Reminds me of a line in the movie Ted, where he explains how he met friend at a fundraiser.