Yes, Levi-Strauss points to incest taboo as universal. I'm not sure if I understand your placement of the explanation as "biological" or "cultural", but isn't Levi-Strauss' explanation cultural in _The Elementary Structures of Kinship_ ? He says the incest taboo develops because marrying "out" of the group is the basis for forming alliances with other groups. If a group marries inward, it will shrivel _socially_. Exogamy is socially, not biologically, caused.
I think he escews the biological explanation. If marrying ( having sex) too close was limited by the production of biologically weaker offspring, then non-human species would likely develop an instinct ( i.e. biological mechanism) against it. The incest taboo is explained as culturally caused by L-S, no ?
The fact that different groups have different definitions of incestual relations supports this. In some societies, certain "first" cousins are _preferred_ mates.
Charles
Chris Doss Incest. This is a perfect case in point of the idea that biologically based behavioral "tendencies" get "worked out" culturally.
Claude Levi-Strauss, one of my intellectual heroes, made the observation that _all_ human societies possess an incest tabu, which while not proof that it is integral to human beings in so far as they are together in large social groups (just saying "all x are y" does not mean that "all x are necessarily y") it is pretty good inductive hint. Assuming that we construe the "essence" of homo sapiens biologically, which we have to do if we are pure materialists, these means that there is probably something biologically inherent in human beings that causes them to look upon incest as something undesirable, even though close relatives are the most accessible sexual partners physically, in most cultures.
He was writing a few decades ago, but as far as I know it is true -- all human societies possess an incest tabu. However, this taboo manifests itself in completely different ways in different societies -- in some, first cousins are off base, while in otherd they are desirable, etc. (And some societies have legislated incest in certain highly specific circumstances, e.g. the Egyptian pharoahs or Polynesian kings marrying their sisters.)
(Of course incest does happen all the time, but it is eschewed by society and usually punished very harshly. Social insects also violate the "laws" of egg-laying, but those eggs get killed by the hive/nest as quickly as they are identified.)
Nu, zayats, pogodi!