The Fallacy of Extreme Genetic Determinism

While attending a recent conference on the west coast, I had some time to read the New York Times and my interest was peaked by the headline on the story below:

Here is a synopsis of the news report.  Gary Cossey had pleaded guilty to to a single count of possessing child pornography.  At the sentencing hearing expert psychologists for the defendant testified that Mr. Cossey was not a high risk repeat offender in-part because he had voluntarily been participating in therapy sessions with signs of responding positively to therapeutic interventions.


Nevertheless, the judge rejected these arguments because it was very likely that Cossey would commit repeated offenses stating: "It is a gene you were born with.  And it is not a gene you can  get rid of,"  Judge Gary Sharpe then sentenced Cossey to a prison term of 6.5-years, a life term of supervised release, and a $100 court fee.


However, a court of appeals overturned the sentence* because there was no evidence to support the assertion that Cossey would inevitably repeat his offenses due to a child pornography gene. Neither is there undisputed evidence that such a gene exist. The appeals court then ordered that another judge be appointed to preside over a re-sentencing hearing to determine a Cossey's final jail sentence.


But what if there were such a gene?  What if it were not a trait that was expressed according to classic laws of Mendelian inheritance, but was a polygenetic trait?  Would it be the case in either instance  that a person with this gene or genes would inevitably be either a consumer or purveyor of child pornography?