While I don't know as I'd jump on the acceptance bandwagon for the boy/girl ratio conclusions, a lot of it fits in with my observations about people and behavior.
The only biological reason for sex is continuation of the species. That we can enjoy sex outside that purpose is beside the point. Males are hardwired to be attracted to women who most likely could have children. That some of us have other tastes is, again, beside the point. The issue is the majority of all males, not any one male. The wide hips deal certainly makes sense.
The commentary about suicide bombers is not unique to these writers. Whle homosexuality may be rampant and a form of sexual relief, it's also a death-penalty offense under Sharia--which must create intolerable psychological pressures. "Damned if you do, damned if you don't." Note that even so, it takes an outside influence such as a mullah to preach/teach/brainwash that self-destruction is the answer, so long as an Infidel goes along for the ride. Islam/Sharia provides a unique and fertile field for suicide bombers.
Which leads to the commentary about the problems with post-puberty into early adulthood. This is well-known, old-hat stuff. Our violent crime rates here peaked around 1993, right along with the peak in the 16-24 age group. Both declined until around 2005, with a subsequent increase now occurring.
As far as the Scandinavian natural selection, I'd guess that it's more a matter of light blue over darker blue. SFAIK, the tendency toward blue-eyed blonds in the population quite possibly predates the movement of the people into that part of the world. If what's claimed about reading the eyes as a source of information for a level of interest is correct, then light blue would convey more to an observer than a darker blue. A guy works on what information he can get...
Something that runs concurrently through much of the list is that power is an aphrodisiac for women. Physical power, financial power, political power: All these are attractive to most women. Sure, not all women--but why would one expect "all"? We're people.
Wandering off a bit: Clinton's an interesting case study for both fitting in with the authors' conclusions and being different. That is, he joked about indoor-outdoor carpet in the bed of his pickup, and getting knee burns. He strove for political power from a fairly early age. Little conscience with his high sex-drive, based on insider comments about him. Yet he married a fairly plain woman who apparently didn't care to have more than one child--as she had and has the same drive for power, albeit possibly for different reasons (I don't know). Power guy tend to have more kids; maybe a pair of power people deliberately stop at one? Ah, well; more questioning than concluding, here...