Hair growth at age 12 is normal development and will not affect your height.
Boys’ sexual development begins at the age of 12 to 14, with enlarged testicles, an enlarged and thicker penis, armpit hair, pubic hair, a thick and deep voice, and a beard on the face. Therefore, hair growth at the age of 12 belongs to normal development, which is a sign of the development of secondary sexual characteristics of the human body, and does not belong to precocious puberty.
And the beginning of the secondary sexual characteristics, there will be rapid growth in height and weight, again showing growth peak, you can supplement calcium, phosphorus, vitamin D and other nutrients, to focus on nutritional balance and adequate, sleep enough, appropriate with physical exercise.
It is worth noting that if a girl’s long hair appears in a manly area, she should consult a doctor in time to find the cause and actively intervene in the treatment.