Hair genetics can come from either parent, and multiple genes can determine hair traits, such as color, texture, and growth.
Genes can also affect hair loss. Although it can run in families, this is not always the case.
This article looks at how genes affect hair traits, including hair loss.
A note about sex and gender
Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Learn more.
Many genes determine hair color, which depends on the amount of melanin in the hair. Little research has been done into the genes involved in hair color, and most research centers around the MC1R gene.
The MC1R gene helps create the melanocortin 1 receptor, which plays a role in melanin production. Activation or deactivation of the receptor determines the type of melanin the cells produce, which determines hair color.
Studies have linked certain genes to differences in hair thickness and texture in particular populations, although many genes are likely involved.
People can inherit hair traits from both parents and according to the American Hair Loss Association (AHLA), many genes affect hair type and growth.
For example, the MC1R gene plays a key role in determining hair color, and people inherit two copies of the gene, one from each parent.
Is male androgenic alopecia inherited from the female parent?
According to the AHLA, it is a myth that people only inherit male androgenic alopecia, more commonly known as male pattern hair loss, from the maternal side or, in particular, from the maternal grandfather.
Researchers still do not fully understand the genetic causes of male androgenic alopecia. However, they think the condition involves multiple genes that a person inherits from both sides of the family.
The androgen receptor (AR) gene is one of the key genes linked to hair loss. It is found on the X chromosome, which male children inherit from the female parent. However, research has also found a similarity in hair loss between male parents and their male children, which mutations in the AR gene cannot solely explain.
Researchers are still working to fully understand the genetic causes of hair loss in male and female pattern baldness, but certain genes may play a key role.
Male androgenic alopecia
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Research suggests mutations in the AR gene are associated with androgenic alopecia. The AR gene helps create androgen receptors, which are proteins that regulate the body’s response to androgens.
Dihydrotestosterone (DHT) is a by-product of testosterone, converted by 5-alpha-reductase enzymes. DHT is present in the oil glands of the hair follicles. Miniaturization is a process in which DHT causes hair follicles to shrink.
In hair follicles with genetic susceptibility, DHT can lead to shorter hair growth. Over time, this decreases the size of the hairs and gradually leads to baldness.
Female androgenic alopecia
According to the AHLA, people previously believed androgen hormones were primarily responsible for female androgenic alopecia, similar to male androgenic alopecia.
However, researchers now think that androgens are not the only cause of hair loss in females, as around 90% of females with androgenic alopecia present with typical androgen levels. However, treatments that target androgens can still be effective for female androgenic alopecia.
The genetics involved in female androgenic alopecia are more complex than those in male androgenic alopecia. Sometimes, there is no significant family history of androgenic alopecia in females with genetic hair loss.
Changes in estrogen signaling, which supports the functioning of the reproductive system, may be an important factor in female pattern baldness.
Factors other than genetics may also contribute to female androgenic alopecia, with hormonal birth control being the leading external cause.
Yes, a person can inherit hair-loss genes from both sides of their family. With male androgenic alopecia, a family history of the condition on either side of the family occurs in around 80% of people with male pattern hair loss.
A person’s hair traits can resemble a parent’s hair but may differ depending on whether people inherit recessive or dominant gene traits.
Hair loss can run in families, and research has found that over 80% of people with noticeable hair loss had a male parent with hair loss.
Factors other than genetics may affect hair loss, including:
- chronic disorders
- nutrition
- drug use
- stress
- tight hairstyles that cause repeated pulling of the hair
Other factors, such as stress, hormonal changes, and aging, can also affect hair color. Chemicals, such as hair relaxers or perms, and certain medications can affect hair texture and thickness.
A simple or complex genetic process follows Mendelian inheritance, which means a single gene causes a specific trait. Hair inheritance is more complex as it is a polygenic process, which means it involves multiple genes.
According to a 2018 article, large-scale research has found 63 loci on chromosomes linking to male androgenic alopecia, six of which occur on the X chromosome. Three loci on the chromosome, including the AR gene, had possible genes linking to hair loss. Loci refers to the location of a gene on a chromosome.
People with certain variations of the AR gene may be more than twice as likely to develop male-pattern baldness compared to those without these variations.
Hair genetics involve multiple genes, which can come from either parent.
Research has identified specific genes linked to certain hair traits, although further research is necessary to understand the role of other genes.
Other factors, such as aging, hormones, and health issues, can also affect hair traits and hair loss.