Brother Sister Incest

Zezima wrote:Ninja, you don't get it. Siblings don't hump each other just "cuz da bible sez it's da sinz!", No. Because inbreeding causes deformities. It's for the good of the human race.

XNinjaRed wrote:

Zezima wrote:Inbreeding causes deformities. It's for the good of the human race.

It barely makes a difference whether they're siblings or not.
Science says so.

Instinctual and Genetic Explanations
One theory, proposed by Havelock Ellis suggests that the taboo expresses a psychological revulsion that people naturally experience at the thought of incest.[10] Most anthropologists reject this explanation, since incest does in fact occur.[11][12][13]

Another theory is the Westermarck effect, first proposed by Edvard Westermarck, that children reared together, regardless of biological relationship, form a sentimental attachment that is by its nature non-erotic.[14] Melford Spiro argued that his observions that unrelated children reared together on Israeli Kibbutzim nevertheless avoided one another as sexual partners confirmed the Westermarck effect.[15] According to another study, however, out of 2516 marriages documented in Israel, only 200 were between couples reared in the same kibbutz. These marriages occurred after young adults reared on kibbutzim had served in the military and encountered tens of thousands of other potential mates, and 200 marriages is higher than what would be expected by chance. Of these 200 marriages, five were between men and women who had been reared together for the first six years of their lives. This research disconfirms the Westermarck hypothesis.[16]

Another theory is that the observance of the taboo would lower the incidence of congenital birth defects caused by inbreeding. This theory was first proposed by jurist Henry Maine, who did not have knowledge of modern genetics, but who did draw on his observations of animal husbandry[17] Anthropologists reject this explanation for two reasons. First, inbreeding does not directly lead to congenital birth defects per se; it leads to an increase in the frequency of homozygotes. [18] An increase in homozygotes has diverging effects. A homozygote encoding a congenital birth defect will produce children with birth defects, but homozygotes that do not encode for congenital birth defects will decrease the number of carriers in a population. The overall consequences of these diverging effects depends in part on the size of the population. In small populations, as long as children born with heritable birth defects die (or are killed) before they reproduce, the ultimate effect of inbreeding will be to decrease the frequency of defective genes in the population; over time the gene pool will be healthier. In larger populations, however, it is more likely that large numbers of carriers will survive and mate, leading to more constant rates of birth defects.[19]

Second, anthropologists have pointed out that the social construct "incest" (and the incest taboo) is not the same thing as the biological phenomenon of "inbreeding". In the Trobriand case a man and the daughter of his father's sister, and a man and the daughter of his mother's sister, are equally distant genetically. Biologists would consider mating in both instances, but Trobrianders consider mating in one case incestuous and in the other, not. Anthropologists have documented a great number of societies where marriages between some first cousins are prohibited as incestuous, while marriages between other first cousins are encouraged. Therefore, the prohibition against incestuous relations in most societies is not based on or motivated by concerns over biological closeness.[20] Nor can it be explained by the effects of inbreeding or natural selection.[21][22]