Characteristics of inbred children include mental and physical abnormalities such as impaired cognition and birth defects, according to a 2014 article in PLOS ONE. Inbreeding increases the frequency with which genetic disorders are expressed, thus causing individuals to exhibit potentially damaging traits.Continue Reading
The harmful effects of inbreeding were first noted by Charles Darwin, who showed that the descendants of two adult organisms too closely related displayed decreased vigor and fertility, explains PLOS ONE. Closely related human adults who produce offspring run the risk of having children who suffer from harmful recessive mutations, such as congenital birth defects, malformations and many other complex disorders. Inbreeding has also been associated with significant decline in average height, weight and body mass index in children.
Evidence about the results of inbreeding among humans is rare, but European royal dynasties practiced it for generations to keep titles in the family and forge political alliances, says Ewen Callaway for Nature Publishing Group. This led to mental and physical disabilities in many of Europe's monarchs and their relatives. King Charles II of Spain was physically and mentally disabled, and he is believed to have suffered from at least two conditions caused by recessive mutations that led to infertility and kidney failure.Learn more about Molecular Biology & DNA