modern DNA evidence suggests that a huge percentage of children back then (some estimates as high as 25%) were not genetically related to their fathers
The surprising result of these new studies is that human EPP rates have stayed nearconstant at around 1% across several human societies over the past several hundred years. This poses an immediate puzzle for behavioural scientists, who estimated that without the availability of modern contraceptives the historical EPP rates should have been much higher, in the range of 10–20%, based on present behavioural measures of EPCs and observed kin investments of matri- and patrilineal family members, which are known to be inversely related to EPP [13]. Hence, it appears that people were more faithful in their relationships in the past, or – put differently – that the recent widespread adoption of modern contraceptives has sexually liberated women, resulting in a relatively greater number of extra-marital affairs, but in EPP rates that have remained as low as they were before.
My only complaint is that the method of study seems like it would not be great at differentiating paternity between relatives (i.e., cases where the affair partner is related to the husband, such as his brother or cousin) due to shared Y chromosomal DNA.
This is not true at all, typical historical rates are 1% or less: https://www.cell.com/pb-assets/journals/trends/ecology-evolu...
The surprising result of these new studies is that human EPP rates have stayed nearconstant at around 1% across several human societies over the past several hundred years. This poses an immediate puzzle for behavioural scientists, who estimated that without the availability of modern contraceptives the historical EPP rates should have been much higher, in the range of 10–20%, based on present behavioural measures of EPCs and observed kin investments of matri- and patrilineal family members, which are known to be inversely related to EPP [13]. Hence, it appears that people were more faithful in their relationships in the past, or – put differently – that the recent widespread adoption of modern contraceptives has sexually liberated women, resulting in a relatively greater number of extra-marital affairs, but in EPP rates that have remained as low as they were before.