A recent case came before the European Court of Human Rights involving a German brother and sister in an incestuous relationship who have had several children together. The couple are in breach of German law and the couple brought Germany before the court saying their rights to a private and family life had been violated.

The court upheld German law saying it is up to individual states to decide their own laws in this regard.

But why do we ban consensual incestuous relationships between adults at all? That is the question asked by this blog, a blog hosted by no less an institution than the University of Oxford.

It can find no good reason why we should ban consensual incest. It even dismisses the usual argument that children produced by such relationships are more likely to have birth defects. (As was indeed the case with two of this couple’s children)

The blogger, one Paul Troop, points out that people with Huntingdon’s disease are quite likely to pass it on to their children but no-one suggests that people with Huntingdon’s disease shouldn’t marry and have children. Why therefore do we single out those in incestuous relationships?

Further, he argues, we don’t ban everything we consider to be wrong. We ban theft mainly because it would become even more widespread if we didn’t. We don’t ban it chiefly because it is wrong in itself.

But if we lift the ban on incest, he says, it will not become widespread because very few siblings are attracted to one another. (The brother and sister in this case were not raised together)

For these and other reasons, Troop says, half of the signatory countries to the European Convention on Human Rights do not ban incest.

Troop’s argument raises two questions. The first is whether we still believe consensual incest between adults is wrong in itself, and the second is whether we should ban it even if we think it is wrong?

Based purely on liberal principles how would a person answer ‘yes’ to the first question  and ‘no’ to the second question? Answers on a postcard please.