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How many men are raising a child that is not their own? What the genetic data show us. 🧵
"A common urban myth is that many fathers are cuckolded into raising children that genetically are not their own."
"Human EPP rates have stayed near constant at around 1% across several human societies over the past several hundred years."
"Human EPP rates have stayed near constant at around 1% across several human societies over the past several hundred years."
Combing genealogies with Y-chromosome haplotyping in an Afrikaaners population revealed the rate of cuckholdry was 0.9% over the last 330 years. 
This finding has been replicated across multiple European populations:
www.nature.com/articles/hdy201536
www.nature.com/articles/hdy201536
The Dutch - only .96%.
"The Dutch EPP rate fits perfectly within the range reported for other contemporary and historical populations in Western Europe."
"The Dutch EPP rate fits perfectly within the range reported for other contemporary and historical populations in Western Europe."
What's interesting about all of these papers is that the genetic estimates are usually close to the historical EPP estimates. They tend to be within a few percentage.
Or, in other words, people have been really good at keeping track of cuckholdry.
Or, in other words, people have been really good at keeping track of cuckholdry.
Even the Himba estimate given by the community was 47% - remarkably close to the study's finding of 48%.
The simple explanation for this is that people know when infidelity is occurring. They find out, sooner or later.
In the case of the Himba it's simply open.
The simple explanation for this is that people know when infidelity is occurring. They find out, sooner or later.
In the case of the Himba it's simply open.
You may have heard that EPP rates are as high as 30%.
If you Google it, you'll find a lot of websites (usually selling paternity tests) claiming this.
I haven't been able to trace it back to a published source with data anywhere.
If you Google it, you'll find a lot of websites (usually selling paternity tests) claiming this.
I haven't been able to trace it back to a published source with data anywhere.
Giving them the benefit of the doubt that it isn't entirely made up, EPP rates from companies that sell paternity tests will overestimate EPP due to selection bias.
It would be better to interpret this as: "1/3 of men who think the child isn't theirs and gets a test to confirm turn out to be right."
At this point I tend to view claims of high EPP as an urban myth more than a legitimate biased overestimate however.
People have heard this figure and just repeat it.
People have heard this figure and just repeat it.
An EPP of 30% would be socially visible in other ways as well - imagine how many living-related kidney donors would be rejected because they weren't really related to the child.
Same with bone marrow donors.
You'd hear about this every week.
Same with bone marrow donors.
You'd hear about this every week.
It might make a mess of heritability estimates in behavioral genetics too, if 1/3 of all children were not actually related to their fathers.
Pretty much anything where you need a sample of fathers and sons who are related to each other.
Pretty much anything where you need a sample of fathers and sons who are related to each other.
Given that these are all estimates that cover large spans of time before birth control existed, you should also expect EPP to remain low now.
Affair or not, women have a great deal of control over their pregnancies.
Affair or not, women have a great deal of control over their pregnancies.
Pair bonding, concealed estrous, short window of fertility, mate guarding, and the remarkably close proximity that human mates share should also make you skeptical of large EPP figures. Just a priori from a behavioral/evolutionary POV.
"The overall chances of conception occurring in these circumstances turn out to be fairly remote (0.23%). This figure is consistent with an estimate by James (1993) that 1 in 400 (0.25%) of non‐identical twins have been fathered by different men." 
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Geoffrey Miller @primalpoly
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Dec 24, 2022
Good thread.