Chin hair, like all body hair, grows in cycles: Anagen (growth phase), Catagen (transitional phase), and Telogen (resting phase). Androgens, male hormones present in both men and women, significantly affect hair growth. An increase in androgen levels or heightened sensitivity to these hormones can result in more noticeable facial hair.

Genetics also play a key role in chin hair growth, influencing the density and distribution of hair follicles. This is why some women naturally have more facial hair than others. Changes in hormone levels, such as during puberty, pregnancy, or menopause, can also impact chin hair growth.