Fidelity is more prevalent than assumed

A very informative tweet thread integrating research over the past decade based in both genealogy and genetics.  

How many men are raising a child that is not their own? What the genetic data show us. 🧵

— Alexander (@datepsych) December 23, 2022

For western Europeans, it appears that non-matched paternity, the father of the child being different from the named father, is about a 1-2% occurrence and has been that low for several hundred years.  Non-matched paternity is also described as extra-pair paternity (EPP.)

The evidence is not as plentiful for non-western cultural traditions but where it does exist, it also is in the vicinity of 1-2%.  

Subject to a wider investigative net, that suggests that wherever there are cultural taboos against maternal infidelity, those taboos are pretty effective at suppressing non-matched paternity.

There is one cultural group for whom a tradition of pair-bonded mating/fidelity is not the norm.  Among the Himba people of Namibia, there is apparently not a high expectation of fidelity.  The community surveyed estimated that only 47% of children would be genetically matched to the named father.  The actual results were 48% - community expectation matched empirical results.  

The thread has plenty of links to studies.

I am surprised at how low the European rate is, particularly on the implied time scale.  Continental Europe in particular has had long periods of time when huge portions of the population were subject to ebbs and flows of armies in occupation or transit.  I would suspect that rape would be highly correlated with martial events and that ought to imply elevated EPP but that is not what is suggested by the research.  Either the rapes are not occurring or they are not resulting in offspring.

It would be interesting to know whether the EPP rates vary by religion (I suspect not and one of the studies suggests not), by class, or by location (more prevalent in city environments?)

Anyway, all this roughly matches the bits and pieces that have caught my eye over the years.  Interesting to see it all in one place and therefore more affirmed than I would have estimated.