Inbreeding facts for kids

Inbreeding is a term used in genetics. It means when closely related animals or plants mate and have offspring. The most extreme type of inbreeding is when a plant fertilizes itself. This happens often in plants that have both male and female parts on the same flower. Inbreeding is the opposite of outcrossing, which is when animals or plants that are not related mate.

For people, marrying or having children with very close relatives has been restricted by almost all cultures around the world. For example, many cultures do not allow marriages between first cousins.

What Happens with Inbreeding?

When inbreeding happens over many generations in a group of animals or plants, it reduces the variety in their genes. This can lead to a few things:

• More chance of getting certain traits: This can be good or bad. If both parents have genes for a helpful trait, like a special color in a flower or speed in a racehorse, their babies are more likely to get two copies of that gene. This makes the trait show up strongly. People sometimes use this in selective breeding to get specific qualities.
• More chance of getting less helpful traits: This is the main worry with inbreeding. Many genes have versions that only cause problems if an animal or plant gets two copies of them (one from each parent). Closely related parents are more likely to carry the same versions of these genes. When their offspring get two copies, it can lead to health problems or make them less able to survive. This is sometimes called "inbreeding depression."
• Harder to adapt to changes: When there is less variety in genes, a group has fewer different "tools" (gene versions) to deal with changes in their environment. This could be new diseases or changes in the weather.

In Nature

Cheetahs are a good example of inbreeding in nature. Thousands of years ago, the number of cheetahs dropped very low. This meant that the cheetahs alive today are all quite closely related. Because of this inbreeding, many young cheetahs do not survive, and it can be hard for them to have successful litters.

Another example is a study on song sparrows living on an island. Sparrows that were inbred had much lower survival rates than those that were not inbred during a very cold winter. These studies show that inbreeding can make it harder for animals to survive when conditions are tough.

Royalty and Nobility

Charles II of Spain, a member of the Habsburg family. He had a very noticeable lower jaw, often called the Habsburg jaw, due to many generations of close family marriages.

In the past, noble and royal families often married each other. This was a way to create political alliances between powerful families. Marriages were seen as a way to join important family lines, not just as a choice between two people.

Royal intermarriage was common among European royal families, usually for reasons of state power. Over time, because there were only a few royal families to marry into, the gene pool of many ruling families became very small. Eventually, almost all European royalty became related to each other. This also meant that many royals were descended from the same person through many different family lines, like the many European royals who are related to British Queen Victoria or King Christian IX of Denmark.

Interesting Facts About Inbreeding

• Animals and plants on islands are often very inbred. This is because they are separated from larger groups on the mainland, which allows natural selection to work on their smaller population.
• Linebreeding is a type of inbreeding. There isn't a clear difference between the two terms, but linebreeding often involves mating individuals with their descendants or two cousins. This method can be used to increase a particular animal's good qualities in a group.
• The House of Habsburg was a famous royal family known for its many marriages between close relatives. The "Habsburg lip" or "Habsburg jaw" (a very noticeable lower jaw) is often mentioned as a physical trait that became common due to this inbreeding.

Related pages

• Breed

Images for kids

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  Common fruit fly females often prefer to mate with their own brothers over unrelated males.

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  Heterozygous

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  White tiger in Gunma Safari Park

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  A kidney disease called polycystic kidney disease is common in the Persian cat breed, affecting almost half of them in some countries.

See also

In Spanish: Endogamia (biología) para niños