Natural hair texture forms during early growth beneath the scalp. Each strand develops based on physical structure and internal composition, resulting in straight, wavy, or curly hair. This texture remains mostly consistent over time and is influenced by multiple factors, including follicle shape, growth direction, protein bonding, and inherited traits. Understanding these factors helps explain why hair behaves the way it does.
1. The Shape of the Hair Follicle
Hair texture depends on the shape of the follicle, which affects how each strand grows. The shape controls how straight or curved the hair becomes as it comes out of the scalp. A more even shape lets the hair grow smoothly, while an uneven shape makes it bend. This shape does not change over time. It plays a major role in how your hair naturally looks.
- A round follicle produces hair that grows straight.
- An oval follicle produces hair that grows in a wavy pattern.
- A flattened or elliptical follicle produces curly or tightly coiled hair.
2. The Angle of Growth
The direction in which the hair exits the scalp also plays a role. When the hair grows straight up from the follicle, it tends to be straight. But if it exits at an angle, it begins to bend, resulting in waves or curls.
3. Protein Bonds Inside the Hair
Hair is made mostly of keratin, a protein structured in three layers: the cuticle is the outer protective layer, the cortex is the middle layer that defines texture and strength, and the medulla is the inner layer that helps support the overall structure of the hair strand.
Inside the cortex, the keratin proteins are held together by different types of chemical bonds:
- Hydrogen bonds – temporary and easily broken by water or heat
- Disulfide bonds – strong, permanent bonds formed between sulfur atoms in amino acids. These define the hair’s permanent shape.
Straight hair has more evenly distributed disulfide bonds, while curly hair has bonds that pull and twist the strand into coils. When you chemically perm or relax hair, you’re actually breaking and reforming these disulfide bonds.
4. Genetics: The Blueprint
Your hair type is written in your DNA. Genes passed down from your parents control the shape of your follicles, the type of keratin produced, and the number of disulfide bonds in your strands. Even within families, hair texture can vary depending on which genes are more active.
5. Hormones and Age
Hair texture can also change over time. Many people notice shifts in curl pattern during puberty, pregnancy, or menopause. Hormonal changes can influence the way follicles behave, sometimes turning straight hair wavy or making curly hair straighter.
Summary
Hair texture is shaped by several factors: the shape of the follicle, the angle of growth, the distribution of protein bonds in the strand, and your genetics. Over time, hormonal changes can also affect how your hair looks and behaves.
