Why does inbreeding cause abnormalities

Ultimately, Stefansson concluded that maybe our taboos against consanguinity, or the marriage of related people, haven't just overestimated existing risks - they've actually covered up potential benefits :. But in spite of the fact that bringing together two alleles of a recessive trait may be bad, there is clearly some biological wisdom in the union of relatively closely related people.

Lest you think I'm simply here to extol the undiscovered benefits of inbreeding, let's look at the the sad story of Charles II, the last King of Spain from the House of Habsburg, who lived from to and reigned from onwards. Through a series of cleverly organized dynastic marriages two centuries previous, the House of Habsburg had acquired massive land holdings that included the Holy Roman Empire now Germany , the Low Countries The Netherlands, Belgium, and Luxembourg and, most importantly, Spain, complete with its massive overseas empire.

The branch of the family that inherited the Spanish throne was loathe to share power with outsiders, and so they hit upon the same solution that countless other monarchies did - if you don't want to share power, then keep it within the family.

Cousins married cousins, uncles married nieces, and second cousins married second cousins. From onward, not a single outsider married into the Spanish royal line. The result of all this was Charles II, quite possibly the most inbred person in history. Charles's ancestry was so ridiculously intertwined that he actually had a higher relationship coefficient than the child of two siblings, and While the previous kings had escaped their already considerable inbreeding relatively unscathed, Charles suffered from massive mental, physical, and emotional disabilities, earning him the nickname El Hechizado , "The Hexed.

According to contemporary writings, he was often described as "big headed" and "weak breast-fed baby". He was unable to speak until the age of 4, and could not walk until the age of 8.

He was short, weak and quite lean and thin. He was described as a person showing very little interest on his surroundings abulic personality. He first marries at 18 and later at 29, leaving no descendency. His first wife talks of his premature ejaculation, while his second spouse complaints about his impotency. He suffers from sporadic hematuria and intestinal problems frequent diarrhea and vomits.

He looked like an old person when he was only 30 years old, suffering from edemas on his feet, legs, abdomen and face. During the last years of his life he barely can stand up, and suffers from hallucinations and convulsive episodes.

His health worsens until his premature death when he was 39, after an episode of fever, abdominal pain, hard breathing and comma [sic]. Charles II also displayed an extreme version of what's known as the Habsburg jaw, a pronounced underbite that had grown progressively more acute over successive royal generations. Charles's great-great-grandfather, Charles I, already had a severe enough underbite that he couldn't chew properly, and as a result suffered lifelong indigestion.

By Charles II's time, he was completely unable to chew, his tongue was so large that he could barely speak intelligibly, and he drooled constantly. His inability to father an heir sparked the War of the Spanish Succession, in which half a million people fought over who should inherit his throne - a deadly outcome that might have been avoided had the Habsburgs not become so completely reliant on inbreeding to preserve control of their empire, which of course they ultimately lost anyway.

Charles II represents the extremest of examples, a sort of worse case scenario for inbreeding. And yet he - or at least a hypothetical person very much like him - remains a sort of benchmark for how people imagine the results of inbred relationships, when the most likely result of even first cousins inbreeding is a more or less healthy child.

This taboo hasn't always been so strong. In fact, two of the top candidates for greatest scientist of all time married their cousins. Albert Einstein's wife, whose maiden name was in fact Elsa Einstein, was a first cousin through Albert's mother and a second cousin through his father.

And, as we previously discussed, Charles Darwin married his first cousin Emma Wedgwood, and in fact their mutual grandparents, Sarah and Josiah Wedgwood, were themselves cousins. To be fair, after three of Darwin's ten children died young, he and his son George conducted studies into whether the family's long tradition of inbreeding had reduced his reproductive fitness. They ultimately decided this wasn't the case, on the rather strange grounds that "the widely different habits of life of men and women in civilized nations, especially among the upper classes, would tend to counterbalance any evil from marriages between healthy and somewhat closely related persons.

Fertility 1 — affects some Jersey and crossbred animals and can cause cows to be empty due to the loss of pregnancy or stillbirth. Fertility 2, 3 and 4 — affects some Holstein-Friesian and crossbred animals and can cause cows to be empty due to the loss of pregnancy or stillbirth.

Tools to prevent inbreeding and recessive gene problems We have two main tools to prevent inbreeding and problems with recessive genes: DataMATE Our DataMATE app makes it easy for our artificial breeding technicians to calculate the risk of a particular mating. Prevent inbreeding with whole herd DNA parentage testing Whole herd DNA parentage testing can also help reduce the risk of inbreeding by correctly matching calves to their sires and dam.

Find out more Contact your LIC rep to find out more about preventing inbreeding and genetic problems. Related content for you. Animal health and DNA testing Keep your cows healthy, productive and protected with the latest DNA technology and our animal testing services. Get regular reproduction advice from our 6 weeks newsletter.

Twitter Facebook LinkedIn Youtube. Inbreeding is the mating of organisms closely related by ancestry. It goes against the biological aim of mating, which is the shuffling of DNA. Genes determine different aspects of your appearance, like hair and eye colour, as well as biological factors such as your blood type. These genes fall into two categories, dominant and recessive.

If one of the genes in the pair is dominant, then the result is you gain the trait of the dominant gene. However, for traits that originate from the recessive gene, you need both genes to be recessive. For example, the gene for brown eyes is dominant and so having just one of these in a pair will result in your eyes being brown.

This is important as certain congenital defects and genetic diseases, such as cystic fibrosis, are carried by recessive alleles. Inbreeding stacks the odds of being born with such conditions against you. As blood-relative mating partners have similar DNA, the changes of them carrying the same recessive gene is greatly increased. According to a study , the rate of near natal and childhood death increases if the child comes from a first cousin union, nearly doubling in certain countries.

Inbreeding, or mating between two closely-related people, is a strong taboo across the world. The potential for sexual abuse and lasting trauma is high, and the odds of inheriting rare genetic diseases goes up exponentially among children who are the result of inbreeding.

But inbreeding still occurs, if extremely rarely. And scientists have few good sources of data on the issue, as there are a number of difficulties in getting data on inbreeding. Self-reporting inbreeding is understandably uncommon, and there are ethical barriers to gathering data without permission. Now, researchers using data from the UK Biobank, a genetic database of around half a million people from the country, have scanned for evidence of inbreeding in the participants.

The found it: A small number, around. Following up with a look at their genomes, the researchers pinpointed a number of health issues that will likely result from their parentage. Scientists from the University of Queensland, in Australia, sifted through some , genomes from people of European ancestry born between and