Question:
Hey man,
Aren’t these hairs already fully terminal? Why won’t they continue to grow like other older people? I mean my terminal length can’t be that much, maybe 2 cm or so at most, and when it reaches a certain level, it won’t grow any longer.
Answer:
Human hair typically grows about 1/2 inch (1 cm) per month. The body controls the length of each type of hair by having each hair follicle go through a period of rest, during which the old hair falls off, and then restarts the growing cycle again. The shorter the time between the rest periods, the shorter the hairs stay. The hair on top of your head doesn’t cycle very often, so that hair grows quite long. The hair on your arms and legs cycles frequently, so those hairs stay short. Your pubic hairs and chest hairs cycle somewhere in between, so they stay a medium length.
While the hairs that you easily see are terminal, the follicles are still cycling more often, which keeps the hair shorter. This will gradually slow down, and your chin hair will get longer. You’ll have to be patient. Many young men cannot grow a full beard until they reach their mid-twenties.