"Interestingly, the Ju/wasi took no position on homosexuality, which seemed unknown. Researchers of other hunter-gatherer societies have also found an absence of homosexuality. Perhaps the Old Way, with its arduous lifestyle does not transmit this quality."
Believe it or not, the rest of the paragraph gets even odder, but I'm going to let that part alone for now, because I've seen "Seven Brides for Seven Brothers" more than once.
Let's think about this for a bit. The !Kung or the San Bushmen or the Ju/wasi don't live in very large groups. And if there is one thing we know about homosexuality, it is that it tends to be very, very hidden in small groups, unless it somehow gets institutionalized. Given that the author's family wasn't able to find out much more about female sexuality beyond "the women know about and have orgasms", I don't think this family can claim to be any kind of expert on what might or might not be going on between the men of this group, the women of this group, or whatever.
Seriously. The only thing dippier than this author writing this (and her editor allowing it to be published) are the fools quoting this as if this is the Last Word not only on this society, but on "original" humans. I feel a great deal of confidence that you could have picked at random a large minority of an arbitrarily chosen town in 1950s America and asked them about homosexuality, and they would have either not known what it was, or believed it Never Happened Here.
Probably see also _The Bible and Homosexuality in Zimbabwe_, Masiiwa Ragies Gunda, who quotes Epprecht, who quotes Peter Garlake, _The Hunter's Vision_. There are apparently rock painting(s) in the Harare area of the San that show men having anal or between the thigh sex with other men, and these are _old_ paintings.