Puberty can absolutely change hair texture, and going from straight hair to wavy or curly hair during adolescence is a well-documented phenomenon. The shift is driven by the surge of sex hormones, particularly androgens, that reshape how hair follicles operate. Because follicle shape determines whether a strand grows straight or curved, hormonal changes that alter the follicle itself can change the hair coming out of it. The experience is common enough that dermatologists consider it a normal variant of development, though the degree of change varies widely from person to person.
What Makes Hair Curly in the First Place
Hair curliness is not a surface feature. It is determined deep inside the skin, at the level of the hair follicle. A perfectly round follicle produces a round fiber that grows straight. An oval or asymmetric follicle produces a fiber that curves. The internal structure of the strand matters too: in curly hair, a specific keratin protein (hHa8) accumulates unevenly, clustering on the concave side of the curve, while in straight hair the same protein is distributed evenly throughout the fiber.1PubMed. Human hair keratin network and curvature This asymmetry is not cosmetic decoration. It is a structural feature baked into the strand as it forms inside the follicle.
The follicle itself is a small organ with its own complex anatomy. At its base sits the dermal papilla, a cluster of specialized cells that act as a kind of command center. The number and behavior of dermal papilla cells influence the size and shape of the hair that gets produced.2PubMed Central. Dermal papilla cell number specifies hair size, shape and cycling and its reduction causes follicular decline When something changes the dermal papilla or the inner root sheath that guides the growing strand, the resulting hair can come out with a different texture than before. This is why hormonal shifts have such outsized power over hair: they act on the follicle’s control center, not just the strand itself.
How Puberty Hormones Reshape the Follicle
The hormonal event that matters most for hair texture changes at puberty is the rise in androgens, particularly testosterone and its more potent derivative dihydrotestosterone (DHT). These hormones surge during puberty in both sexes, though more dramatically in boys. Dermal papilla cells contain androgen receptors, meaning they can directly detect and respond to circulating androgens.3PubMed. Balding hair follicle dermal papilla cells contain higher levels of androgen receptors than those from non-balding scalp When androgens bind to these receptors, they trigger changes in gene expression within the follicle that can alter everything from hair thickness to growth cycle length to the follicle’s physical shape.
The effects of androgens on hair are famously contradictory. They stimulate thick, dark hair growth on the face, chest, and pubic area while, in genetically susceptible people, they eventually shrink scalp follicles and cause balding. Research has shown that dermal papilla cells from different body sites respond to the same androgens in opposite ways: beard follicle cells are stimulated to produce growth-promoting signals, while scalp follicle cells from balding areas are inhibited by androgens.4PubMed. The hair follicle: a paradoxical androgen target organ These paradoxical differences appear to be hardwired into the follicle from embryonic development, which is why the same hormone can make one patch of hair flourish while another thins out.
For scalp hair texture specifically, the androgen surge at puberty can change the cross-sectional shape of the follicle. A follicle that was round in childhood may become more oval under hormonal influence, and that geometric change is enough to shift hair from straight to wavy or from wavy to curly. The process is gradual. Most people notice the change over months or years during adolescence, not overnight. And because each follicle is semi-independent, you can end up with a transitional period where some strands are curly and others are still straight, which many teenagers experience as sudden unmanageable frizz.
Why It Happens to Some People and Not Others
If every teenager gets an androgen surge, why do only some of them end up with curlier hair? The answer is largely genetic. Your DNA determines both the baseline shape of your follicles and how sensitive those follicles are to hormonal signaling. The most well-studied gene linked to hair curliness in Europeans is trichohyalin (TCHH), which encodes a protein expressed in the inner root sheath of the follicle. Variants in the TCHH gene are strongly associated with straight hair and account for a measurable portion of the variation in hair shape across populations.5PubMed Central. Common variants in the trichohyalin gene are associated with straight hair in Europeans
But TCHH is far from the whole story. A genome-wide study in South Africa identified additional links to a copper transporter protein called CUTC and to keratin 74, another inner root sheath component.6PubMed. The biology and genetics of curly hair Hair curliness is a classic polygenic trait, meaning many genes contribute small effects that add up. Some of these genes may control follicle geometry directly, while others may influence how aggressively the follicle responds to androgens during puberty. If you inherited a set of variants that makes your follicles particularly androgen-responsive, the hormonal changes of adolescence could push your hair texture noticeably toward the curly end of the spectrum. If your follicles are less responsive, the same hormonal surge might leave your hair essentially unchanged.
This genetic backdrop explains a few things people notice. First, puberty-related hair changes tend to run in families. If a parent’s hair got curlier at puberty, their children have a higher chance of the same experience. Second, the change is more common in certain ethnic groups, which reflects population-level differences in the frequency of follicle-shaping gene variants. Third, not everyone’s change goes in the same direction. Some people’s hair gets straighter at puberty rather than curlier, and some find their hair gets coarser or darker without any change in curl pattern. All of these outcomes reflect different genetic combinations interacting with the same hormonal trigger.
Puberty Is Not the Only Time Hair Texture Can Shift
Puberty gets the most attention because it is dramatic and universal, but the underlying principle that hormones can reshape follicles applies at other life stages too. Pregnancy is one of the most commonly reported triggers for hair texture changes. The massive fluctuations in estrogen and progesterone can thicken hair, change its curl pattern, or alter its oiliness. Some women find their hair becomes straighter during pregnancy and returns to its original texture afterward; others report the opposite. The postpartum period, with its sharp hormone drop, brings its own round of texture shifts along with the well-known postpartum shedding phase.
Menopause is another hormonal inflection point. As estrogen declines and the relative influence of androgens increases, some women notice their hair becoming thinner, coarser, or differently textured. This is a milder version of the same androgen-follicle interaction that occurs during puberty, just driven by a different hormonal context. Men experience analogous gradual changes through midlife as testosterone levels shift and follicle sensitivity evolves with age.
Thyroid disorders deserve a mention here because they are commonly missed. Both hypothyroidism and hyperthyroidism can change hair texture, sometimes producing coarser, drier, or differently curled hair. Unlike puberty, which is a one-time developmental transition, thyroid imbalances produce hair changes that are potentially reversible with treatment. If your hair texture changes suddenly in adulthood without an obvious hormonal milestone like pregnancy or menopause, a thyroid check is a reasonable step.
Acquired Progressive Kinking
There is a specific clinical condition worth knowing about, called acquired progressive kinking of the hair, in which patches of hair become tightly curled and take on a texture resembling pubic hair. It tends to appear in males and is associated with a darkening of the affected hair in roughly two-thirds of patients.7JAMA Network (Archives of Dermatology). Acquired progressive kinking of the hair This is a distinct condition from normal puberty-related texture changes, and it can occur at various ages. It is considered an acquired disorder of hair formation rather than a genetic trait, and its differential diagnosis includes both inherited kinky-hair syndromes and hair changes from chemical or mechanical damage.7JAMA Network (Archives of Dermatology). Acquired progressive kinking of the hair
The reason this matters for anyone wondering about puberty-related curl changes is that it helps draw a line between normal variation and something that might warrant a dermatologist’s attention. If your hair got generally wavier or curlier during your teenage years and the change was gradual and diffuse, that is overwhelmingly likely to be a normal hormonal texture shift. If patches of hair suddenly become extremely tightly kinked, are noticeably different from surrounding hair, or are accompanied by darkening or brittleness, that is a different situation and worth getting evaluated.
Will the Change Stick Around?
One of the first questions people ask when their hair starts changing during puberty is whether the new texture is permanent. In most cases, the answer is yes, at least for the long term. The hormonal changes of puberty are not temporary fluctuations; they represent a permanent shift in baseline hormone levels as the body transitions from a prepubertal to a postpubertal state. Follicles that have been reshaped by this transition generally stay in their new configuration.
That said, hair texture is never truly fixed for life. The same person may notice subtle shifts in their twenties, after pregnancies, during hormonal contraceptive use, or in later decades as aging gradually changes follicle behavior. Some people who got curlier at puberty find their hair slowly relaxes in their thirties or forties. Others find the curl intensifies. These shifts are smaller and slower than the puberty-era change but they reinforce the broader point: hair texture is not a static trait locked in at birth. It is a dynamic output of follicle biology that responds to hormonal environment throughout life.
For practical purposes, if your hair became curly during puberty and you are now well past adolescence, treating it as your permanent texture is reasonable. Products and routines designed for curly hair will generally serve you well. If you are in the middle of the transition, it can be worth waiting before committing to expensive treatments or drastic cuts, because the final texture may not be obvious until your late teens or early twenties when hormonal levels stabilize.
Managing a Texture Transition
The practical side of a puberty-related texture change catches a lot of people off guard. You have spent years learning how to manage one kind of hair, and suddenly the rules change. Straight-hair routines often make newly curly hair worse: daily shampooing strips oils that curly hair needs, brushing dry curly hair creates frizz, and products designed for fine straight hair weigh curls down without providing enough moisture.
A few general principles tend to help during the transition:
- Less washing: Curly hair is structurally more prone to dryness because the bends in the strand make it harder for sebum to travel from root to tip. Washing every two to three days rather than daily helps retain natural moisture.
- Conditioner over shampoo: Prioritizing a good conditioner and using a gentler, sulfate-free shampoo can make a substantial difference in frizz and definition.
- Detangling wet: Curly hair tangles easily and breaks when brushed dry. A wide-tooth comb or fingers on wet, conditioned hair is the gentlest approach.
- Accepting the learning curve: Figuring out your specific curl pattern, porosity, and ideal products takes experimentation. What works for one curl type may not work for another, and advice from friends with different textures can be misleading.
It is also worth noting that curly hair is more vulnerable to mechanical breakage than straight hair. The bends in each strand create stress points where damage accumulates. Heat styling, tight ponytails, and harsh chemical treatments do more damage to curly hair per exposure than to straight hair. If you are newly curly and used to flat-ironing or blow-drying daily, reducing heat use will help the transition go more smoothly.
The Reverse Scenario and Other Unexpected Shifts
While the question usually focuses on straight-to-curly transitions, the reverse happens too. Some children with curly hair find their curls loosen or disappear at puberty, ending up with wavy or straight hair as adults. The mechanism is the same in principle: hormones reshape follicles, and the direction of that reshaping depends on genetics. Because social expectations and beauty norms often frame curliness as the notable change, the loss of childhood curls gets less attention, but it is equally common and equally normal.
Beyond curl pattern, puberty frequently changes hair in other ways that can be confusing if you are only watching for curl. Hair may get oilier as sebaceous glands ramp up under androgen stimulation. It can darken, sometimes dramatically, as melanocyte activity in the follicle increases. Texture can shift from fine to coarse, or vice versa. These changes often happen simultaneously with curl pattern shifts, making it hard to tease apart which specific change is causing your hair to look and feel so different from what you are used to. The oiliness, in particular, tends to peak in the mid-teen years and then gradually settle down, so the greasy-and-frizzy combination many teenagers experience is often a temporary worst-case scenario rather than a permanent state.
Medications can also trigger texture changes that mimic or overlap with puberty-related shifts. Hormonal contraceptives, which are often started during or shortly after puberty, can affect hair texture independently of the underlying developmental changes. Some formulations contain progestins with androgenic activity, which can push hair in the same direction puberty was already taking it. Others are anti-androgenic and may counteract puberty-related curl changes. If you started a new medication around the same time your hair changed, it can be difficult to tell how much of the shift was developmental and how much was pharmacological.
Ethnicity, Population Genetics, and Why the Science Is Thin
Research on hair curliness has historically been underfunded compared to other areas of dermatology, and what does exist tends to skew heavily toward European populations. The largest genetic studies linking specific genes to hair shape, including the TCHH work, were conducted primarily in people of European descent.5PubMed Central. Common variants in the trichohyalin gene are associated with straight hair in Europeans More recent work has begun to expand the picture, with genome-wide studies in South African populations identifying different genetic contributors to curliness.6PubMed. The biology and genetics of curly hair But the genetics of hair texture across global populations remains poorly mapped.
This matters because the experience of puberty-related hair change is not uniform across ethnicities, and generalizing from one population’s genetics to another’s is unreliable. In populations where tightly coiled hair is the norm, puberty may change hair thickness or density without much visible change in curl pattern. In populations where straight hair predominates, even a modest shift toward waviness can feel dramatic. The subjective experience of “my hair got curly” is shaped by expectations as much as by biology, and those expectations are population-specific. Dermatological research has a long way to go before it can offer population-specific guidance on what hair texture changes to expect at puberty and why.
What the existing research does make clear is that follicle shape, keratin distribution, and hormonal responsiveness are all under genetic control, that these genetic factors vary substantially across populations, and that puberty provides the hormonal environment in which those genetic predispositions are finally expressed. Your childhood hair is not necessarily your “real” hair. It is the version of your hair that existed before your follicles had been exposed to adult hormone levels. The texture that emerges during and after puberty is, in a very real biological sense, the version your genes were always going to produce once the hormonal conditions were right.