Some men go bald on the top of their head though they may be having hair on the sides and on the back of the head; it happens due to the deficiency of certain hormones in the body and due to over-stess and tension taking by them in their profession.
What you are describing is common of male pattern baldness,the hair on top is affected by male hormones after pueberty. Family history tells what will happen and most receding hairlines happen by age 40.
