Just How Common is Paternity Surprise?

paternity surpriseBBC News and other media are reporting how a recent DNA test result reveals that the Archbishop of Canterbury was not fathered by whom he believed had been his dad.

The Most Reverend Justin Welby, 60, is reported to have said that the identity of his real biological father has come as a “complete surprise.” The Archbishop has now found out that he is, in fact, the son of Sir Winston Churchill’s last private secretary, the late Sir Anthony Montague Browne.

Before the DNA test Justin Welby had considered his father to have been a whiskey salesman named Gavin Welby, who died in 1977.

His mother, Lady Williams of Elvel, has now also confirmed, according to the BBC News website, that she had a “liaison” with Sir Anthony just before she married in 1955.

This news might add to the widespread belief, fueled by the kind of paternity tests that have become referred to in gossip magazines, talk shows and ‘trailer trash’ TV, that many fathers are deceived into raising children who are not theirs genetically.

Extra-Pair Paternity

The common urban myth is that there are extraordinarily high rates of what geneticists refer to as ‘extra-pair paternity,’ or EPP. Quotations of estimates typically range from 10–30%.

Perhaps one reason for these high estimations is that female adultery is supposedly common, occurring in an estimated 5–27% for people younger than 30 years old, depending on which survey you consider.

Some evolutionary biologists and psychologists even speculate that some females may also be driven biologically, through evolutionary selection pressures, to actively seek ‘extra-pair copulations.’ This might be a way to improve the genetic diversity and biological quality of offspring, argue evolutionary biologists and could be an insurance against male infertility.

Another evolutionary psychology theory is that extra-pair copulations allow women to have the best of both worlds. They obtain the benefits of parenting and fathering from more reliable domestic ‘safe’ types of male, even as they bear the genes of a child fathered by more exciting ‘alpha-male’ ‘hunter’ types.

But now a new investigation and review of the academic area, by scientists at the University of Leuven, Belgium, and the Department of Genetics, University of Leicester, is arguing that ‘extra-pair paternity’ in contemporary human populations is only 1–2%.

The study, by Maarten Larmuseau, Koen Matthijs and Tom Wenseleers, contends that the previously inflated figures are not representative of the general population, partly because they were mainly based on data from paternity testing laboratories where paternity was disputed.

Critics, however, of these lower recent estimates from genetic techniques, which  have only become available over the past decade, point out that in historical times, ‘extra-pair paternity’ rates might well have been much higher, because of the lack of reliable contraception.

The era when the Archbishop of Canterbury’s mother had that “liaison,” was back in 1955.

The authors of this new investigation, entitled ‘Cuckolded Fathers Rare in Human Populations’, due to be published shortly in the academic journal, Trends in Ecology & Evolution, quote another recent study that did find a slight but significant decrease in ‘extra-pair paternity’ events following the introduction of the birth control pill.

Just How Common is Paternity Surprise?