Contemporary families and alternative lifestyles Book

Helen Fisher sounded so interesting years ago on a NPR interview, I made a note to read this book. Took me 10 or 15 years to get to it. Maybe that was the problem, although I think not. Her technique is to discuss mating practices across myriad species, and meld that with statistics on human behavior. OK, fair enough, although there is vast room for selection bias. But after doing all that, she offers her theory with nothing more than: "Perhaps humans have the same impulse as the tse-tse fly in that.... " Oy vey. Almost every chapter ends like that. Yes, perhaps we do, Dr. Fisher -- OR, perhaps we don't! All that research, much of which is more widely known today than when she was writing this, seemed only a cover for interjecting her own thought. Which did not necessarily seem based on the research as a whole; rather, on just one aspect of it that she had seized upon for that particular point she wanted to make. I slogged and slogged through it, repeatedly disappointed by this technique, and finally reached the last chapter "Sex in the Future," and could not make myself pick the book up again.