Are IQ tests really the best way to measure nature vs nurture?

I have a dim memory from 1970 of a primly dressed distant relative visiting in a Baby Austin. This, I later learned, was the anthropologist Beatrice Blackwood. I googled her 45 years later and was astonished to find she had spent several years in the 1920s and 1930s living alone among Stone Age tribes in New Guinea. Her pet kitten so enchanted the normally fierce Kukukuku that they even built her a temporary house. Aside from her travels, what also surprised me was how close-knit the world of anthropology then was. Just a few hundred people gave rise to debates which are still alive today. Nature vs nurture, for instance. Or IQ testing.

Blackwood was a close friend of Hortense Powdermaker, who was later to write a fascinating study of Hollywood called Hollywood, the Dream Factory. She and Powdermaker shared an intense dislike of Margaret Mead, whose Coming of Age in Samoa depicted a kind of paradise of guilt-free casual sex among Samoan teens, implying sexual mores were merely social constructs.