Reviewed by Vicky Davis, FNP
Written by Our Editorial Team
Genetics can be mysterious: You might have curly hair while your sibling has straight hair. Your mom might have blue eyes while yours are brown. The list of differences, often small, goes on, with your genes playing a role in countless important traits.
But in addition to affecting your eye color and hair texture, your genes can also offer insight into your current health, your future health, and in some cases, your ability to grow a full, thick head of hair and maintain it as you get older.
Yes, hair growth is genetic. However, there’s far more to your hair’s growth rate and your risk of dealing with a form of hair loss than a single “baldness gene.”
Below, we’ve discussed the relationship between your genes and your hair, from how a range of genetic factors may affect your hair’s thickness, shade and texture to how genetic factors play a role in common hair-related issues, such as male pattern baldness.
We’ve also explained your options for slowing down, stopping and reversing hair loss caused by genetic factors, from FDA-approved medications to surgical procedures.
Your genes play a role in just about every aspect of your appearance, from the precise shape of your nose, jawline and other facial features to your height, bone structure, skin tone and general body composition.
Research also shows that genetic factors can affect numerous aspects of your hair, from texture and color to the size of your hair follicles and the thickness of your scalp hair.
For example, studies have found that your hair color is determined by several genes that control the production of melanin in your hair follicles, including the well-known and widely-studied gene MC1R, which regulates production of a protein called the melanocortin 1 receptor.
Genes that control the production of eumelanin regulate whether your hair is black or blond. As the eumelanin content of hair increases, it can vary in color from a light blond tone (caused by a low level of eumelanin) to black (high levels of eumelanin).
Red hair, on the other hand, is linked to high levels of a genetically-determined pigment referred to as pheomelanin.
Your genes also determine the natural texture and thickness of your hair. Experts have identified specific genes that could be responsible for variations in hair texture and size that result in curly hair, wavy hair or straight hair.
Put simply, your genes play a role in just about every aspect of your hair’s appearance, at least when it comes to how it looks in its natural state.
So, can your genes also play a role in hair growth? Simply put, yes. Your genes are involved in several aspects of your hair’s ability to grow, from your hair growth cycle to your risk of common hair-related issues such as male pattern baldness (androgenetic alopecia, or genetic hair loss).
Your genes affect your levels of hair growth and overall hair health in several ways, including by changing your production of hormones that can influence hair follicle development and result in loss of hair on your scalp.
If you’ve ever looked up information about the hormonal side of hair loss, you might have seen references to male sex hormones called androgens.
Androgens, such as testosterone, play a major role in the development of your male secondary sex characteristics. From your bone structure to your voice, body hair and anatomy, if you have a feature that’s masculine in nature, testosterone is probably at least partly responsible.
Testosterone and related androgens also factor into hair growth, and certain androgens created as byproducts of testosterone can cause a type of hair loss called male pattern baldness.
More specifically, the androgen hormone dihydrotestosterone (DHT), which your body produces from a small percentage of your total testosterone, can attach to receptors located in your scalp and cause your hair follicles to miniaturize over time.
These miniaturized hair follicles gradually become less capable of completing the hair cycle that stimulates hair growth.
Normally, your hair follicles go through several distinct phases as each new hair grows to its full length. This cycle includes the anagen phase, or growth phase, in which new, normal hair grows from the follicle over the course of several years.
It also includes the catagen phase, in which your hair becomes inactive, and the telogen phase, in which your hair rests and eventually sheds, allowing a new hair to take its place.
As hair follicles miniaturize, each follicle spends less time in the anagen phase, resulting in hair that’s thinner, shorter and lacking in hair structure proteins.
Over time, these smaller, thinner hairs can fail to penetrate through the outer layer of your skin, resulting in a visible pattern of hair loss such as a receding hairline, a bald spot near the crown of your head, or moderate-to-severe hair loss across your entire scalp.
Our guide to DHT and male hair loss goes into more detail about this process, as well as what you might notice if you’re beginning to experience DHT-related balding.
As you might have already guessed, your genes play a significant part in this process. In fact, the official name for male pattern baldness -- androgenetic alopecia -- clearly suggests that a mix of androgens and genetic factors are responsible for this type of hair loss.
Experts believe that some men go bald sooner than others, or in different ways, due to genetic factors such as an excessive response to androgen hormones in the hair follicles.
Put more simply, genetic variations may cause some men to have hair follicles that suffer from the effects of DHT faster than those of other men. This variation in DHT sensitivity is likely why some men have complete baldness in their 20s or 30s, while others only have mild hair loss.
Contrary to popular belief, there’s no evidence to suggest that this sensitivity to DHT is inherited from your mother’s side of the family, that bald or balding men have more testosterone, or other common hair loss myths.
However, it’s clear that genes you inherit from your parents -- likely from both sides of the family -- are involved in your hair’s ability to grow as you get older.
Recent studies using biomedical databases have allowed researchers to learn more than ever about the effects of genes on your risk of hereditary hair loss.
In a study published in the journal PLoS Genetics in 2017, researchers used data from the UK Biobank covering more than 52,000 men aged between 40 and 69 to uncover upwards of 250 genetic loci associated with severe hair loss.
Over time, this type of research may allow researchers to more specifically pinpoint the genes that are responsible for hair loss in men and women.
In addition to affecting your sensitivity to DHT, your genes can also influence your risk of certain health conditions that may affect your hair growth.
Although male pattern baldness is the most common type of hair loss amongst men, it’s not the only issue that can cause you to lose hair. Many medical conditions, including hormonal issues, autoimmune disorders and nutritional deficiencies, can also cause moderate hair loss.
For example, a genetic autoimmune disorder called alopecia areata can cause patchy hair loss that results in small, circular areas of baldness on your scalp and face.
Other conditions affected by your genes, such as hypothyroidism (low thyroid hormone levels) can contribute to telogen effluvium, a type of temporary abnormal hair loss that happens when your hair’s natural growth cycle is interrupted.
Currently, research suggests that the length of your hair is likely determined by both genes and your hair care habits.
Your hair grows to its full length during the anagen phase of the hair growth cycle. This phase can last anywhere from two to six years, allowing your hair to grow down to your shoulders or theoretically all the way to your lower back, provided you don’t cut it.
Since your genes play a key role in the length of your hair’s anagen phase, they do have some impact on your hair’s ability to grow to its full length.
However, for most people, hair length isn’t determined solely by genetic factors. Instead, it’s the end result of hair care habits -- namely, getting regular haircuts.
If you get your hair trimmed on a frequent basis, it’s unlikely that your genes will limit the length of your hair. Focus on good hair care habits and you’ll be able to grow your hair as long as you like, provided you’re ready to take action to treat male pattern baldness if it develops.
Although there’s currently no way to reverse genetic hair loss, there are several evidence-based hair loss treatments available that can either slow down or stop male pattern baldness.
Some men who use these treatments also experience improvements in hair growth as dormant, inactive hair follicles start producing new hairs again.
Currently, the most effective options for treating genetic hair loss are the medications finasteride and minoxidil.
Finasteride is a prescription medication that works by preventing your body from being able to convert testosterone into DHT.
By preventing this conversion, finasteride drastically reduces DHT levels throughout your body, shielding your hair follicles from the damaging effects of DHT.
Finasteride begins working right away to reduce DHT levels, but it can take up to 12 months for it to produce any noticeable improvements in your hair loss pattern or general hair density.
However, these changes do eventually occur for most men, with one study finding that upwards of 80 percent of balding men who use minoxidil show signs of improvement after one year.
We offer finasteride online, following a consultation with a licensed healthcare provider who will determine if a prescription is appropriate.
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Minoxidil is an over-the-counter hair loss medication that’s available as a liquid or foam. While it doesn’t reduce DHT production like finasteride, it does promote hair growth by shifting your hair into an active growth state and stimulating blood flow to your scalp.
If you have slight hair loss around your hairline or crown, using minoxidil may help to speed up the growth process and add additional hair coverage.
Minoxidil can be used on its own, but it appears to be especially effective when it’s used at the same time as finasteride. For example, research shows that more than 94 percent of men with hair loss show improvements after using both medications for one year.
Another option for dealing with genetic hair loss, albeit more extreme and less common, is hair transplant surgery. This is a procedure that involves moving DHT-resistant hairs from the back and sides of your scalp to your hairline and other areas affected by hereditary hair loss.
Hair transplant surgery can vary in price and complexity, with several techniques used to move hair follicles to affected areas of your scalp. Our guide to hair transplants goes into more detail about this procedure, as well as its major advantages and disadvantages.
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While we still don’t know precisely which genes are responsible for hair growth (and likely won’t for some time), there’s overwhelming evidence that your genes play a critical role in the growth of your hair, as well as your risk of developing male pattern baldness.
In short, you have your parents, grandparents and great-grandparents to thank (or not) for most aspects of your hair, from your hairline to certain conditions that may affect your hair health and long-term hair growth.
If you’re beginning to notice the early signs of baldness and want to take action, you should take a serious look at hair loss treatments such as finasteride and minoxidil.
If your hair loss is causing you to feel anxious or stressed, talking to a counselor could also help you to feel better and think constructively about how to best maintain your hair.
Dr. Vicky Davis is a board-certified Family Nurse Practitioner with over 20 years of experience in clinical practice, leadership and education.
Dr. Davis' expertise include direct patient care and many years working in clinical research to bring evidence-based care to patients and their families.
She is also an active member of the American Academy of Nurse Practitioners.