Here are five of the most persistent hair growth myths over the decades, and what the science actually says about each one, reviewed by a scientist.
Myth 1: Shaving Your Head Makes Hair Grow Back Thicker and Faster
This is probably the most widely believed hair myth out there, and it's easy to see why: shaved hair often does look coarser and darker as it regrows. But that's an optical illusion. The thing is, hair grows from the follicle beneath the skin, and shaving only removes the part of the hair shaft above the surface - it has zero effect whatsoever on the hair follicle itself (aside from slight mechanical forces), which is where thickness, growth rate, and color are actually determined. What you're seeing after a shave is the blunt-cut tip of each hair, which feels coarser to the touch than a naturally tapered end, combined with the fact that regrowing stubble hasn't yet been lightened by sun exposure. The rate of growth and eventual thickness are completely unchanged.
The takeaway: Shave as often as you like for the look, but it won't change how your hair grows back.
Myth 2: Wearing Hats or Helmets Causes Hair Loss
The theory behind this myth is that some hats may restrict blood flow or "suffocate" the scalp, causing hair to fall out. In truth, hair follicles get their oxygen and nutrients from blood vessels connected to the dermal papilla deep under the skin - not from surface airflow - so a hat sitting on top of your head has no meaningful effect on the oxygen supply.
There is a very narrow exception: headwear worn so tightly, for so many hours a day, that it constantly pulls on the hair shaft can contribute to traction alopecia over time. But that's a mechanical stress issue tied to tension, not a "lack of air" issue. It also applies to tight braids and ponytails far more than it does to an ordinary hat or helmet.
The takeaway: Your baseball cap isn't causing your hairline to recede. If it feels uncomfortably tight for hours daily, loosen it — but casual hat-wearing is not a hair loss risk factor.
Myth 3: You Only Inherit Hair Loss From Your Mother's Side
This one has just enough scientific basis to be believable, which is part of why it's so persistent. The androgen receptor gene, which plays a significant role in androgenetic alopecia (pattern hair loss), sits on the X chromosome - and since men inherit their only X chromosome from their mother, this gene specifically does come from the maternal line.
But that's only one gene among many involved. Research has identified dozens of genetic variants across multiple chromosomes - inherited from both parents - that contribute to your overall risk and pattern of hair loss. A father with a full head of hair doesn't cancel out other paternal genetic contributions, and a father with significant hair loss is itself a meaningful risk signal, not something to dismiss because "it's really about mom's side."
The takeaway: Your mother's family history does matter, but so does your father's (nice try guys!). Pattern hair loss is polygenic, so you have to look at both sides of your family.
Myth 4: Brushing More or Trimming Often Makes Hair Grow Faster
Hair growth happens entirely below the scalp's surface, inside the follicle - nothing you do to the visible hair shaft (brushing, trimming, oiling) can speed up or slow down that underlying biological process. Similar to Myth 1, trimming split ends does prevent breakage that can make hair look like it's not growing by keeping length from snapping off, but it doesn't change the rate at which the hair follicles produce new hair.
Brushing has a real but limited role: gentle brushing distributes natural oils and can help move hairs that are already in the exogen (shedding) phase along, but excessive or aggressive brushing can cause breakage and irritate the scalp - working against the appearance of healthy hair.
The takeaway: Trim to manage breakage and split ends, not to "encourage" hair growth - the two are not biologically connected.
Myth 5: Hair Loss Only Happens to Older Men
Androgenetic alopecia is often pictured as something that happens to men in their 50s and 60s, but that undersells both how early it can start and how commonly it affects women. Pattern hair loss can begin in a person's 20s, and research suggests a substantial share of men show some degree of it by age 35. Women are affected too - female pattern hair loss is common, though it tends to present differently, as diffuse thinning along the part line rather than a receding hairline, and isn't driven by androgens in the same direct way as it is in men.
Believing hair loss is an "older men only" issue leads to two problems: younger people dismiss early warning signs, and women often go undiagnosed longer because clinicians and patients alike aren't looking for it.
The takeaway: Hair loss is common, not rare, and it doesn't wait for a particular age or apply to one gender only. Early thinning at any age is worth paying attention to.
Why These Myths Matter
None of these misconceptions are simple, harmless trivia - several of them can actively delay someone from seeking an accurate diagnosis or starting treatment while a genetic form of hair loss is still in its earlier, more treatable stages. For example, RE:YOU’s Dual-Path Hair Revival Serum is the perfect partner to combat thinning hair. In a 100+-person clinical study, 50% of participants saw more hair growth than minoxidil (the current gold standard treatment) when analyzed by machine for 90 days, while 97% of users had less hair loss as measured by combing and hair counting.
If you're noticing changes in your hair and aren't sure whether what you're seeing fits a normal pattern or signals something worth addressing, a dermatologist can help clarify that far more reliably than folk wisdom can.