Why do men become bald?

Both, men and women may be affected equally by temporary hair loss due to stress, skin infection, disease, drug or radiation-induced side effects. Permanent baldness, seen mostly in men, is genetically governed. The gene for baldness is present on the X-chromosome. However, it does not express itself if a normal version is present on the partner chromosome. Since women have two X-chromosomes and men only one, a woman may carry a copy of the baldness gene on one X-chromosome with the other X-chromosome being normal. In such a case, the woman will not go bald. However, a copy of the baldness gene on the single X-chromosome of men predisposes them to the trait. It is unlikely (though not impossible) for a woman to carry copies of the baldness gene on both X-chromosomes. The tradition of keeping long hair allows women to cover patches of baldness better than men in whom the baldness shows.