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 06, 2020
Chemistry & Physics
The Most Powerful X-ray Source On Earth
NOV 06, 2020
The Most Powerful X-ray Source On Earth
Located inside the Sandia National Laboratories in Albuquerque, New Mexico, the Z Pulsed Power Facility (or Z Machine) i ...
NOV 12, 2020
Chemistry & Physics
Can a Chemical Be Both Nurturing and Destructive?
NOV 12, 2020
Can a Chemical Be Both Nurturing and Destructive?
On August 4, a megascale explosion almost leveled half of Beirut, the capital city of Lebanon. At the center of the negl ...
DEC 28, 2020
Immunology
What Happens When Your Immune System Works Against You?!
DEC 28, 2020
What Happens When Your Immune System Works Against You?!
Our immune system is our army against any molecule that wants to invade our bodies like viruses, bacteria, and cancer. I ...
MAR 26, 2021
Plants & Animals
A Massive 17-Year Cicada Swarm will Emerge Soon
MAR 26, 2021
A Massive 17-Year Cicada Swarm will Emerge Soon
The east coast is preparing for one of nature’s greatest spectacles. A gigantic swarm of periodical cicadas is due ...
JUN 21, 2021
Space & Astronomy
Scientists Detect Signatures of Life on Earth Remotely
JUN 21, 2021
Scientists Detect Signatures of Life on Earth Remotely
An international team led by researchers from the University of Bern in Switzerland and the National Centre of Competenc ...
OCT 29, 2021
Health & Medicine
Can Playing Tetris Help Patients with PTSD?
OCT 29, 2021
Can Playing Tetris Help Patients with PTSD?
Intrusive memories are one of the most harmful symptoms of Post-Traumatic Stress Disorder, or PTSD. Intrusive thoughts a ...
Loading Comments...