Pickled Politics asks whether they should be banned.
No, I dunno. There´s conflict there between consenting adults being able to do as they wish (and being prepared to accept the consequences of course) and the damage that will/might be inflicted upon the offspring of such. The sort of moral maze that I´m not competent to find my way through I´m afraid.
But if more people were told about the effects of such cousin marriages we might well see less of them:
Habsburg rule over Spain ended in 1700, only two centuries after it began, with the death of Charles II. He was a sickly, disabled and mentally retarded man, whose poor health and childlessness were probably explained by his inbred inheritance, scientists have shown. A study led by Gonzalo Alvarez, of the University of Santiago de Compostela, has indicated that Charles II suffered from two separate rare genetic conditions, which were almost certainly the result of his ancestors’ marriage patterns.
Charles II, known as El Hechizado (The Hexed), was short and weak, and suffered from rickets, intestinal problems and blood in the urine. He had learning difficulties, a large head relative to his body size, and his two wives reported that he suffered from impotence or premature ejaculation. Dr Alvarez’s team said that his symptoms would have been well explained by two recessive genetic disorders: combined pituitary hormone deficiency and distal renal tubular acidosis.
His genetic background – including that his father, Philip IV, and mother, Mariana of Austria, were uncle and niece – “could explain most of the complex clinical profile of this king, including his impotence/infertility which in last instance led to the extinction of the dynasty”, the researchers concluded.
The Habsburgs’ poor prospects were further compounded by an extremely high rate of mortality in infancy and childhood, which may also have been a result of their inbred character. Half of all royal children died before the age of 10, compared with only 20 per cent of children born in ordinary Spanish villages in the same period.
Given that the purpose of marriage is to have children (alright, only in a Darwinian sense but still….) the evidence that first cousin marriages makes having children moot as your line will/could die out should reduce the incidence, no?