Hair loss doesn’t come from just one side of the family. The old claim that baldness comes from your mother’s side has a grain of truth, but it’s far from the full picture. Both parents contribute genes that influence whether you’ll lose your hair, how early it starts, and how far it progresses.
Why People Blame the Mother’s Side
This belief isn’t pure myth. One of the most influential genes for male pattern baldness sits on the X chromosome, which men inherit exclusively from their mothers. This gene affects how sensitive your hair follicles are to hormones, and it plays a meaningful role in hair loss risk. Since men get their single X chromosome from mom, it’s easy to see why “look at your mother’s father” became common advice.
But that single gene is just one piece of a much larger puzzle. A large genetic study of over 52,000 men from the UK Biobank identified 287 independent regions of the genome linked to male pattern baldness. Of those, 247 were on non-sex chromosomes, meaning they come equally from both parents. Only 40 were on the X chromosome. So roughly 86% of the identified genetic signals for baldness have nothing to do with which side of the family you look at.
Both Parents Contribute
Research published in the Journal of Investigative Dermatology found a strong resemblance in baldness patterns between fathers and sons, but noted this didn’t fit a simple single-gene inheritance model. The researchers concluded that hair loss has a polygenic cause, meaning dozens or hundreds of genes each nudge your risk up or down. You inherit half of these from your father and half from your mother.
Harvard Health Publishing puts it plainly: contrary to the folk wisdom that baldness is inherited from one’s mother’s family, the condition depends on genes contributed by both parents. If your father is bald, that raises your risk. If your maternal grandfather is bald, that also raises your risk. Having baldness on both sides increases it further. But none of these family patterns guarantee anything, because with so many genes involved, the combinations are unpredictable.
How These Genes Actually Cause Hair Loss
The genetics of hair loss work through your body’s hormone system. An enzyme converts testosterone into a more potent form called DHT. When DHT binds to receptors on hair follicles, particularly at the temples and crown, those follicles gradually shrink. Each growth cycle produces a thinner, shorter, lighter hair until eventually the follicle stops producing visible hair altogether. This process is called miniaturization, and it’s why balding is gradual rather than sudden.
The genes you inherit determine how much of that enzyme you produce, how sensitive your follicle receptors are to DHT, and how quickly the miniaturization process unfolds. Some of those genes come from mom’s side, some from dad’s. The X-chromosome gene primarily influences receptor sensitivity, which is why it gets so much attention, but enzyme production and other factors are controlled by genes on other chromosomes.
What This Means for Predicting Your Risk
There’s no reliable way to predict hair loss based on one relative. Looking at your mother’s father gives you some information, but so does looking at your father, your father’s father, and your siblings. The more relatives on either side who experienced hair loss, the higher your statistical risk. But because hair loss involves hundreds of genetic variants combining in complex ways, some men go bald with no obvious family history, while others keep a full head of hair despite bald relatives on both sides.
The typical progression follows a recognizable pattern. It often starts with a receding hairline at the temples, forming an M or V shape, sometimes combined with thinning at the crown. In less common cases, the hairline moves straight back without creating that island of hair in the middle. The rate varies enormously. Some men notice significant thinning in their twenties, while others don’t see changes until their fifties or later.
Hair Loss in Women Works Differently
For women, the inheritance pattern is even less clear-cut. Female pattern hair loss tends to appear as diffuse thinning across the top of the scalp rather than a receding hairline. Having a first-degree relative with hair loss, whether that’s a parent or sibling of either sex, increases your likelihood. The same principle applies: genes from both sides of the family matter, and no single relative’s hair predicts yours.
Women’s hair loss also tends to start later, often after menopause, and is influenced by hormonal shifts that interact with those inherited genetic tendencies. The genetic architecture overlaps with male pattern baldness but isn’t identical, which is part of why the pattern of thinning looks different.
Environment Plays a Role Too
Your genes set the stage, but they aren’t the only factor. Environmental and lifestyle influences affect when and how severely hair loss genes express themselves. Researchers acknowledge that many of these environmental factors remain poorly understood, but stress, nutrition, and hormonal changes from medical conditions or medications can all accelerate or delay genetically programmed hair loss. Two brothers with nearly identical genetics can lose their hair at different rates depending on their overall health and life circumstances.
The bottom line: if you’re scanning family photos trying to predict your future hairline, look at both sides. The mother’s-side myth captures about 14% of the genetic story. The rest comes from everywhere in your family tree.