MAR 28, 2016 12:53 PM PDT

Why is Inbreeding a Bad Idea?

WRITTEN BY: Xuan Pham

Over the course of history, marrying within families was not an unusual practice, especially in families of royalty descent. Inbreeding, or the consanguineous union of two closely related family members, was a way to maintain and keep the line of power within a single lineage. However, it soon was apparent that this method of preserving power had detrimental health effects. It is thought that the hemophilia disease that spread throughout the European royalties in the 19th and 20th century began and propagated because of consanguineous marriages.

Today many countries have laws that prevent incestuous relationships and such unions are often considered taboo. But how does inbreeding increase the risks of genetic abnormalities in a population?

Genetically speaking, the union of two closely related individuals increases the chances that alleles of a gene are the same - this is what geneticists refer to as homozygosity. In some conditions, two recessive alleles are needed for the disease to occur, and inbreeding ups the chances of this happening. Thus conditions that require two bad alleles, like cystic fibrosis or Tay-Sachs disease, occur in higher frequency from consanguineous marriages. Conversely, outbreeding decreases the chances of homozygosity because there are more different alleles to be shuffled in the offspring.

The effects of inbreeding are useful for geneticists in the context of disease at the population level. Inbreeding is also useful in mouse genetics, where it is an advantage to have genetically identical mice for experimental purposes. Watch the video to learn more about what happens when we inbreed other species.
About the Author
  • I am a human geneticist, passionate about telling stories to make science more engaging and approachable. Find more of my writing at the Hopkins BioMedical Odyssey blog and at TheGeneTwist.com.
You May Also Like
NOV 10, 2018
Videos
NOV 10, 2018
Engineering Viable Offspring From Same-sex Mouse Parents
Using a special kind of stem cell and genetic engineering, researchers have learned more about what's possible in reproduction....
NOV 11, 2018
Health & Medicine
NOV 11, 2018
Stop Procrastinating, It's Not Good for You
Procrastination is common, but some people procrastinate much more than others. Those who do it persistently probably exhibit something known as chronic pr...
NOV 14, 2018
Videos
NOV 14, 2018
The Sunscreen Gene
Wouldn't it be convenient if we didn't have to worry about sunscreen because our bodies were able to just make it when we needed it?...
NOV 27, 2018
Chemistry & Physics
NOV 27, 2018
Unraveling the Secret Behind the Strength of Spider Web
You don't need to watch a Spider-Man movie to notice how tough a spider web can be. Made of fiber-based spider silk, the seemingly fragile structure ca...
DEC 03, 2018
Health & Medicine
DEC 03, 2018
Why Do Some Men Have Trouble Growing Beards?
There are two types of men in this world: those that can grow robust beards, and those that can’t. But why is it that some men get stuck with patchy,...
DEC 10, 2018
Space & Astronomy
DEC 10, 2018
Learn More About How NASA Built the Parker Solar Probe
When NASA built the Solar Parker Probe to embark on its mission to study the Sun, they knew it’d need to be built with bleeding-edge technology to ma...
Loading Comments...