Why does hair grow after trimming but remains at a constant length after a while?

Question

Some hair especially body hair regrows after trimming but stops growing after a while. What is the mechanism behind control of hair growth and how is the length limit determined?

Answer 1

The answer is genetics! Your hair genes tell you hair follicle to produce for a certain amount of time. This is programmed for each stand and after the time is up, or the length is reached, the hair either stops growing or enters the resting phase after which it falls out and a new strand grows in place of it.

Hope that helps!