Humans, unlike most other mamals, are a Sexual Crypsis species. Sexual Crypsis means the female doesn't go into heat or otherwise display her fertility. This appears to be an evolutionary adaptation for creating ambiguity about fatherhood and enabling cuckolding.

DNA analysis has shown that of all men that ever lived, only 40% reproduced. That said, sampling a number of primitive and modern cultures, its a rough constant that 15% of men die "childless". I estimate that ~50% of all men ever, were cuckolded.

In birds, another Sexual Crypsis species, the rate is similar.

The reality of this is a blind spot for men, and society seems to collude in keeping it that way.

http://canadiancrc.com/newspaper_articles/Globe_and_Mail_Moms_Little_secret_14DEC02.aspx

A British survey conducted between 1988 and 1996 by Robin Baker, a former professor at the University of Manchester, confirmed the 10-per-cent figure. That seems high to skeptics such as Dalhousie University geneticist Paul Neumann, although even he admitted that "my colleague, who's a woman, tells me women have no trouble believing it. . . . It's the men who can't."

In the early 1970s, a schoolteacher in southern England assigned a class science project in which his students were to find out the blood types of their parents. The students were then to use this information to deduce their own blood types (because a gene from each parent determines your blood type, in most instances only a certain number of combinations are possible). Instead, 30 per cent of the students discovered their dads were not their biologically fathers. [based on the statistical distribution of bloodtypes and the genetic rules for blood type inheritance, there would have been a 57% rate of cuckolding in order to get a 30% rate of impossible blood type inheritances]

AF/BB is not just a female sexual strategy, but is an evolutionary adaptation, implemented at a physiological level.

.. [hospital] lawyers advise that the child is to be considered the patient, whose needs trump those of the parents. Since telling the father could trigger a breakup and leave the child without proper support, the hospital keeps the secret. Sometimes it can be a whopper.

AF/BB and the extent of cuckolding is humanity's dirty little secret.

DNA testing changes the landscape of this pervasive form of fraud. Write Paternity Testing into your prenups, and make sure you use an independent testing facility that is responsible only to you.

Ask your female friends how they feel about paternity fraud - what would they do if they were married to one man and got pregnant to another? What would they do if they knew one of their friends was deceiving her husband about paternity?