Many men develop new areas of hair growth well past puberty. For example, some men cannot grow a full beard until late in their 20s. New hair may also grow on the arms and legs, chest, back and stomach. In almost all cases, this hair growth is normal even if its not attractive. Hair growth patterns tend to run in families. So I wouldnt be surprised if your father or brothers have hair on their shoulders too.
Women may also grow unsightly body hair in places such as the face, breasts and arms. Often, this is normal. But sometimes this hair growth is caused by an underlying hormone imbalance. (The medical term for this condition is hirsutism.) Typically, hirsutism results from too much testosterone or testosterone-like hormones. And its usually associated with irregular menstrual cycles or infertility. One of the most common causes of hirsutism in women is polycystic ovarian syndrome (PCOS).
Is excess hair growth in men ever abnormal? Rarely. Certain medications like the high blood pressure drug minoxidil can cause dramatic hair growth all over the body. Hirsutism can also be part of certain rare genetic disorders. But hair growth in men is almost never caused by hormone conditions or other serious medical problems.