There are two reasons for the scarcity of male armpit hair: one, the hair follicles under the skin of the armpit are not sensitive to the stimulation of the androgen testosterone or do not respond at all, so that even if the body contains a high concentration of testosterone, it will not grow out of the armpit hair. The actual fact is that the actual body is suffering from a disease that causes the male to not grow armpit hair, this phenomenon will appear when accompanied by other conditions. This has a certain relationship with genetic development. The specific point is that each person’s body will have androgen and estrogen, male androgen is much greater than estrogen, so the performance of long beard, grow more body hair. Few armpit hairs can only indicate that estrogen is a little more than the average male’s, the other does not have any effect. After the development of puberty, the armpit hair of men not only gradually increases, presenting the typical male angularity. Men who do not grow armpit hair may have a problem of stunted development. Especially if you are over 18 years old and still don’t have armpit hair, you should seriously check it out.