John Murphy reviews Sex at Dawn:
[The authors] don’t dispense pat predictions about how “a more relaxed and tolerant approach to fidelity” might play out....Ryan and Jethá compare the slow advances granted to gay rights and same-sex marriage. Ryan and Jethá realize the odds against such tolerance attained by advocates of “free love”, however ethically conceived by those daringly liberated.
Eric Michael Johnson also levels judgment. Several readers have found this line of argument wanting. A reader writes:
I was amused by this item, particularly by the suggestion that tolerance of sexual infidelity might actually strengthen relationships. My experience, admittedly narrow, suggests that this is untrue.
The speculation that women may be less tolerant of infidelity (or more likely to be faithful) because they have been culturally punished for it for so long is interesting. However, it is also possible that women are less tolerant because they have been physically harmed by it. The stories of women who have contracted syphillis from unfaithful husbands are plentiful, and with the modern array of STDs women have all the more reason to hope and expect that their partners will eschew the occasional fling with someone else--whether male or female.
Another adds:
If someone really wants to make a genetic argument, we should look at the great apes. Lo and behold, they have a completely different sexual norm. An alpha male has a harem of females. Perhaps women should just accept their role in life; it's in our genes. The real argument seems to be that genetics, even if they're meaningful, are nowhere near the whole story. Are we to believe that birds distinguish making love to one another from a random fling?