What do you think about the idea that some of your behaviors may be naturally selected through the process of evolution?
A scientist named Edward Osborne Wilson introduced the field of sociobiology in the 70's, which in time led to the development of evolutionary psychology. He argued that an evolutionary framework may prove useful in understanding animal behavior, including the behavior of humans.
Many critics are indeed wary of the ethical implications of thinking about human behavior as determined in part by genes. There's concern that such thinking can be used in support of eugenics, the attempt to improve humans by selective breeding. Wilson's intent, however, was never for sociobiology to justify any behavior, only to understand its evolution.
Wilson argued that the universal incest taboo is driven by our genes.
Why would we need a taboo against incest if it was already in our genes? That's part of the problem with human behavior genetics. We have two kinds of inheritance: genetic and cultural. Some think culture cannot do anything that is contrary to natural selection, while others argue that cultural evolution is so fast that it frees us from our genetic heritage.