Take a look at taboo

It is ironic, if not irresponsible, to suggest we reassess our moral attitude to incest when we fear the family is under threat ("Heart steers head onto right track", THES , January 24).

Our distant ancestors lacked birth control and genetic theory, although according to evolutionary thinkers the benefits of out-breeding vigour were evident in improved survival rates and competitive advantage.

The avoidance of in-breeding is only one hypothesis about the incest taboo.

Others, such as role confusion between kin, suggest a powerful lighting up of the emotional side of the brain.

Another hypothesis is that the incest taboo forced people to seek mates beyond the family, thus underwriting the institution of exogamy, and the foundation of wider social interaction. Perhaps reviewing our attitude to incest might renew interest in the place of the family in society, as a place to search for sexual partners? If you think kinship is important, it is wry to contemplate that reconsidering incestuous relations could plausibly revive the family's beleaguered fortunes, as an increasingly marginalised institution in our culture. At what expense to society and our emotional selves?

Paul Sillitoe
University of Durham