By far the most common form of baldness is that caused by hereditary tendencies in men (androgenic alopecia). If your father or grandfather was bald, you have a good chance of developing the same problem. Baldness is a gender linked genetic condition that is very rare in women, but passes through the female line to men in later generations. There are no cures available, and none are likely for some time to come.
Apart from the hereditary type which is common, there are many causes for patchy or diffuse hair loss including ageing, skin diseases, stress, the menopause, lack of iron or zinc, an under active thyroid gland, drugs (particularly those used to treat cancer) and a dozen or more rare diseases.
Some people, particularly young women, develop patches of baldness that are scattered across their scalp. This condition is known as alopecia, and is very difficult to treat. Many cases settle by themselves after some months or years, but most require prolonged care by a dermatologist.
Almost always male pattern baldness commences with gradual hair loss, starting at the front of the scalp on either side, or in a circular area on top. It is usually accompanied by excess hair on the body due to higher levels of testosterone. The connection between baldness and sexual potency is unproved.