New biological studies suggest that couples consisting of third cousins have the highest reproductive success. Scientists came to their conclusions after studying the records of more than 160,000 Icelandic couples with members born between 1800 and 1965. The results of the study are constant throughout the generations analyzed. Women born between 1800 and 1824 who mated with a third cousin had significantly more children and grandchildren (4.04 and 9.17, respectively) than women who hooked up with someone no closer than an eighth cousin (3.34 and 7.31). Those proportions held up among women born more than a century later when couples were, on average, having fewer children.
Furthermore, these new studies suggest that mating with a relative can reduce the chances of having miscarriages. One evolutionary argument for mating with a relative is that it might reduce a woman's chance of having a miscarriage caused by immunological incompatibility between a mother and her child. Some individuals have an antigen (a protein that can launch an immune response) on the surface of their red blood cells called a rhesus factor—commonly abbreviated "Rh." In some cases—typically during a second pregnancy—when a woman gets pregnant, she and her fetus may have incompatible blood cells, which could trigger the mother's immune system to treat the fetus as a foreign intruder, causing a miscarriage. This occurrence is less probable if the parents are closely related, because their blood makeup is more likely to match.
In view of History, some incestuous relationships were tolerated. Examples of these are:
The Graeco-Roman period of Egyptian history. Numerous papyri and the Roman census declarations attest to many husbands and wives being brother and sister. Some of these incestuous relationships were in the royal family, especially the Ptolemies; the famous Cleopatra VII was married to her younger brother, Ptolemy XIII. Her mother and father, Cleopatra V and Ptolemy XII, had also been brother and sister.
In Ancient Greece, Spartan King Leonidas I, hero of the legendary Battle of Thermopylae, was married to his niece Gorgo, daughter of his half brother Cleomenes I. Greek law allowed marriage between a brother and sister if they had different mothers. For example, some accounts say that Elpinice was for a time married to her half-brother Cimon.
In view of Ethics, incestuous relationships, although immoral, should not be banned. These ethical arguments for the issue Incest are as follows: 1. Incest is taboo without a clear rationale as to why Incest has been bashed for centuries by society. But, beyond repeating the mantra that it is "unnatural and contrary to the history and tradition of the family institution", there is not much substantive argument surrounding why incest between consenting adults is supposed to be wrong. Reproduction between blood relatives does contain some risks, but is there a well-founded argument against its morality beyond this? Not really. If two individuals deeply love one another, why is wrong for them to follow their desire?
2. Incest must be harmful and not just "immoral" to be banned. There are many things that are immoral that are still legal. Adultery, for instance, is typically legal, although it is widely considered immoral. Similarly, incest cannot be illegal merely because it is considered immoral. It must have some significant harmful effect, for which this side argues it does not.
3. Citizens must tolerate "immorality" such as incest. The case against incest is based on an application of biblical rules that have little to do with today’s inclusive and tolerant principles. Modern citizens must learn to live with people who perform deeds they consider abhorrent, but which do not directly harm other individuals. Citizens can certainly protest, but to ban outright a certain practice on the simple basis of "immorality" is unacceptable in modern...