Human Biology The Consequences of Marrying Your Cousin (Genetic Disorder Documentary) |

Wtf is this? 

@dyno why are they doing it in English? They’re not the ones that are doing it.  

@james genetic disorders duh 

Disorders From Inbreeding

The risk of a child developing an autosomal recessive disorder increases with inbreeding. Carriers of a recessive disorder may be unaware they possess a mutated gene because two copies of a recessive allele are needed for gene expression. On the other hand, autosomal dominant disorders are seen in the parents but might be eliminated through inbreeding if the parents carry the normal gene. Examples of defects seen with inbreeding include:

• Reduced fertility
• Reduced birth rate
• Higher infant and child mortality
• Smaller adult size
• Reduced immune function
• Increased risk of cardiovascular disease
• Increased facial asymmetry
• Increased risk of genetic disorders

Examples of specific genetic disorders associated with inbreeding include schizophrenia, limb malformation, blindness, congenital heart disease, and neonatal diabetes.

The House of Habsburg may be the best example of the effects of inbreeding in humans. The Spanish Habsburg dynasty endured for six centuries, largely from consanguinous marriages. The last ruler of the line, Charles II of Spain, displayed a number of physical problems and was unable to produce an heir. Experts believe inbreeding lead to the extinction of the royal line.

Animal Inbreeding

Successive inbreeding of animals has been used to establish "pure" lines for scientific research. Experiments conducted on these subjects are valuable because genetic variation can't skew the results.

In domestic animals, inbreeding often results in a trade-off where a desirable trait is magnified at the expense of another. For example, inbreeding Holstein dairy cattle has led to increased milk production, but the cows are more difficult to breed.

Many wild animals naturally avoid inbreeding, but there are exceptions. For example, banded mongoose females often mate with male siblings or their father. Female fruit flies prefer to mate with their brothers. The male Adactylidium mite always mates with its daughters. In some species, the advantages of inbreeding may outweigh the risks.

Sources

• Griffiths AJ, Miller JH, Suzuki DT, Lewontin RC, Gelbart WM (1999). An introduction to genetic analysis. New York: W. H. Freeman. pp. 726–727. ISBN 0-7167-3771-X.
• Lieberman D, Tooby J, Cosmides L (April 2003). "Does morality have a biological basis? An empirical test of the factors governing moral sentiments relating to incest". Proceedings. Biological Sciences. 270 (1517): 819–26. doi:10.1098/rspb.2002.2290. 
• Thornhill NW (1993).The Natural History of Inbreeding and Outbreeding: Theoretical and Empirical Perspectives