It’s buried away in paragraph 13 of Colm Keena’s report in the Irish Times today, which doesn’t really do this news justice. Another blow for liberty is about to be struck against the repression and cruelty of Catholic Ireland:

“The commission will also look at the law on incest, which criminalises vaginal sexual intercourse between blood relatives.

Consenting intercourse between an adult brother and sister, even if there is no risk of pregnancy, is a crime. “One might question if such conduct should be criminal.””

Proper order, too. For too long Irish brothers and sisters (and, one assumes, brothers and brothers and sisters and sisters) have had to hide their lust for each other away, fearful of the knock of the crozier on the door from interfering religious busybodies wanting to prosecute them for just showing that little bit too much sibling love.

Jokes aside, what on earth is going on here?

The commission’s spokesman in this case is NUI law lecturer Tom O’Malley, who, by virtue of his many legal qualifications, at least deserves a hearing. His argument appears to be that the criminalisation of incest should stop “where there is no risk of pregnancy”, but not where there is. To some extent, there’s a logic to that, as the risk of a child being brought into the world, and being brought into it with a disability arising from inbreeding, is the primary reason for the ban on incest to begin with.

But it’s not the only reason, is it?

“As University of Miami psychologists Debra Lieberman and Adam Smith pointed out in a recent article in the journal Current Directions in Psychological Science, humans have social and psychological mechanisms to deter incest. With very few exceptions, marriages between brothers and sisters and between parents and their children are verboten in every human culture. The primary psychological anti-incest mechanism is the yuck response. Even the idea of sex with mom or dad or bro or sis is upsetting to most people. The psychologist Jonathan Haidt has found that nearly everyone is repelled by the prospect of brother-sister sex, even in hypothetical situations in which there is no chance of pregnancy (here).”

When something as biologically ingrained as the instinctive revulsion towards incest is cast aside, and an incestuous relationship takes place, we can be relatively sure that something in that relationship has gone fundamentally wrong.

Indeed, one of the few proper studies of this subject found that sibling incest was potentially a key indicator of maltreatment during childhood:

“Moreover, the results indicated that the offending behaviour in the sibling incest group was more severe. The study gives some empirical support for the possibility that sibling incest can be one sign, among others, of maltreatment during childhood.”

The other point, of course, is that lawyers often believe that bans on things are only effective if they can be enforced. The idea being that if a brother and sister are genuinely committing consensual incest, it would be almost impossible to uncover, and harder still to prove – so, they might ask, what’s the point of the ban?

The answer is that our laws do not, in fact, simply exist so that they might be enforced. Often, our laws exist as little more than statements about what is, and is not, acceptable in society. That’s why the penalties for so many of them amount to little more than a fine and a slap on the wrist. We’re not going to jail you for speeding on the motorway – but the limits are in place to save lives.

When you take away the legal statement on incest, you take away a good chunk of the argument against it. If you’re somebody unlucky enough to find yourself pressured by a sibling, or the subject of sexually aggressive emotional abuse, you’re no longer able to say “but it’s illegal”, while they are now positively able to say “but there’s nothing wrong with it”.

The law provides us powerful moral signals as to what kind of behaviour is, and is not, acceptable. The net effect of this specific proposal is to make incest more morally acceptable.

There won’t be many winners from that, in the long run,