Understanding Baby Hair Textures and Curl Patterns

Baby hair can seem surprisingly unpredictable: two straight-haired parents may have a child with soft waves, while a curly-haired parent may initially have a baby with almost no visible curl. That is because hair texture is shaped by follicle anatomy, hair-shaft biology, developmental timing and many inherited gene variants rather than one simple “curly” or “straight” gene.

What creates a baby’s hair texture?

Hair texture describes the physical form of the hair fibre: straight, wavy, curly or tightly coiled. It is separate from hair colour, quantity and growth speed, although these features can change alongside one another in early childhood.

The follicle sets the basic pattern

The hair follicle is a small skin organ that produces each individual hair. Its shape and angle beneath the scalp have a major influence on the emerging fibre.

• More symmetrical, round follicles tend to produce straighter shafts.
• Slightly curved or oval follicles more often produce waves.
• Curved, hook-like follicles and markedly elliptical shafts are associated with curls and coils.
• The direction of growth also matters. Follicles positioned at different angles can create cowlicks, whorls and areas that appear curlier than others.

A curly fibre is not simply a straight fibre that has been twisted after it leaves the scalp. Within a curved follicle, cells may be laid down unevenly along different sides of the growing shaft. This produces a fibre that bends repeatedly as it emerges. Hair-shaft cross-section contributes too: straight hair is often closer to circular in section, whereas curlier hair is commonly more oval or flattened. These are tendencies, not rules that can identify an individual child.

Calibre, density and texture are different traits

Parents often say a baby has “thick hair” when they may mean one of three things. Hair calibre is the width of each strand. Density is the number of follicles per area of scalp. Volume is the visible fullness created by density, calibre, curl pattern and length. A child can have fine individual strands but very dense hair, or coarse strands with relatively low density.

Fine newborn hair does not reliably mean that the child will have fine hair later. A mature terminal hair fibre is usually wider and more pigmented than the early hairs seen in infancy.

The genetics behind straight, wavy and curly hair

Hair texture is polygenic, meaning that many gene variants contribute small or moderate effects. Family resemblance is informative, especially when patterns recur across siblings, grandparents and cousins, but it cannot provide a precise percentage chance for a particular curl type.

Genes researchers have linked to hair form

Several genes are associated with aspects of hair shape, diameter or follicle development. Their effects vary between populations and interact with one another.

Gene or locus	Known biological role	Possible relevance to visible hair traits
EDAR	Signals during development of hair follicles, teeth and sweat glands	Variants are associated with thicker, straighter hair shafts in some East Asian populations.
TCHH	Produces trichohyalin, a protein involved in shaping the inner root sheath	Common variants have been associated with hair curliness, particularly in European-ancestry studies.
PRSS53	Active in the hair follicle and linked to calcium handling in hair formation	Associated with straight-to-curly variation in genome-wide studies.
KRT71	Encodes a keratin important in the inner root sheath	Rare disruptive variants can alter hair shape; research also supports a role in curl biology.
PAX3	Helps regulate development of neural crest-derived pigment cells	More relevant to pigmentation and facial development, but may travel with visible family hair traits in ancestry-based patterns.

Genes commonly discussed for colouring, such as MC1R, OCA2, HERC2 and TYR, chiefly influence pigment pathways rather than curl pattern. SLC24A5 contributes to variation in skin pigmentation, while RUNX2 has important roles in skeletal and craniofacial development. These genes do not let anyone read a baby’s future hair texture from a single DNA result.

When one parent has loose waves and the other has tight curls, their child may inherit any blend of the relevant variants. The result may be curls, waves, straight-looking hair with a curlier underlayer, or texture that changes as the shaft matures. A parent’s hair can also differ across the scalp, so family descriptions such as “straight” or “curly” are often less precise than they sound.

Why newborn hair often changes

The hair present at birth is not necessarily the hair that will define childhood. Hair follicles begin forming during fetal development, with scalp follicle development progressing broadly from the second trimester. Before birth, the body is covered by fine lanugo, much of which is shed before delivery. The scalp hair visible in a newborn may be soft, sparse, uneven or surprisingly full, but it is still responding to a changing hormonal environment.

The common shedding phase

Many babies lose some or much of their birth hair between about two and six months. This is usually a normal synchronised shift of follicles into the resting, or telogen, phase after birth. Replacement hair can grow in a different colour, density or texture. A baby born with silky straight hair may later grow waves; another born with dark curls may temporarily become sparse before new hair appears.

Friction can make loss look more dramatic at the back of the head, where a young baby rests against a mattress. This does not normally damage the follicles. Persistent scaling, inflammation, sharply defined bald patches, broken hairs or poor growth should be discussed with a GP, health visitor or paediatric clinician.

When curl pattern becomes visible

Texture becomes easier to judge once replacement hairs have grown long enough to express their natural bend. Even then, the pattern may continue evolving through childhood as follicles enlarge, shafts become more robust and grooming habits reveal or disguise waves.

Age	What is commonly visible	How dependable is the texture?
Birth to 12 months	Birth hair, patchy regrowth, soft fine fibres and temporary shedding	Low; early hair frequently changes.
Age 3	More established density and a recognisable straight, wavy or curly tendency	Moderate; the basic pattern is often apparent.
Age 6	Longer fibres show ringlets, wave grouping, frizz tendency and strand calibre more clearly	Moderately high, though gradual change remains normal.
Age 10	Childhood texture is usually consistent across several growth cycles	High for the pre-pubertal pattern.
Age 18	Puberty-related hormonal changes may affect oiliness, diameter and apparent curl definition	High, but hair can still alter in adulthood.

At age three, an image can reasonably represent a broad texture family, such as loose waves or springy curls, but not every individual curl’s eventual diameter or distribution. By six and ten, the inherited pattern is generally more legible. At eighteen, it is sensible to allow for the influence of puberty on scalp oil production and hair-fibre behaviour.

Environmental influences: real, but not a change of genes

Genes establish the developmental potential of the follicle, but the hair seen on a particular day is also affected by water, humidity, damage and care. Humidity forms and disrupts hydrogen bonds in the hair shaft, so wavy and curly hair may look straighter when stretched wet and more defined as it dries. Brushing dry curls can separate curl clumps and create a fuller, less defined appearance.

Frequent heat styling, bleaching and harsh chemical treatments can change the visible pattern by damaging the cuticle and cortex, but they do not rewrite the genes in the follicle. In young children, gentle cleansing, conditioner suited to the hair’s dryness, wide-tooth detangling and avoiding tight styles that pull on the scalp are usually more useful than trying to force a particular texture.

Frequently asked questions

Can two straight-haired parents have a curly-haired baby?

Yes. Both parents may carry combinations of variants associated with curl or wave formation that are not strongly visible in their own hair. Texture also reflects contributions from wider family lines, and a child’s follicles can combine inherited effects in a new way. It is possible, but no responsible assessment can assign a universal probability without detailed family and genetic information.

Does shaving a baby’s hair make it grow back thicker?

No. Shaving cuts the shaft above the skin and does not alter follicle number, hair diameter or growth rate. Regrowing hair may feel coarser because its cut end is blunt rather than naturally tapered, creating the impression of thickness.

Why is my baby’s hair curly underneath but straight on top?

Follicles vary across the scalp in orientation, shape and growth cycle. The underlayer may also be less exposed to friction, sun and brushing. Mixed textures are extremely common, particularly during the years when childhood hair is replacing early infant hair.

Will my child’s curls disappear at puberty?

They may loosen, tighten or become more prone to oiliness and frizz, but they do not always disappear. Hormonal changes can affect follicle activity and fibre diameter. The direction and degree of change differ between individuals, even within the same family.