My 19 year old son had two back to back, very stressful surgeries (to correct a deformaty in his chest bones) almost a year ago. He always had extremely thick hair up until the month he was in the hospital and on serious pain meds. I told him it was the anesthesia and that it would grow back. Is there something we should be doing to help it grow back? As far as I know, I do not have hair loss in my family tree. I read the other entries, but they mostly were about women and certainly not about a young man sooo young.
Just because you have not identified genetic hair loss in your family, does not mean that he did not get it. Genetic hair loss can skip generations. Sounds like he may have it. Best way to find out is to get his hair mapped out for miniaturization and then you will know. Propecia (finasteride) is a great medication for this, provided that the diagnosis is genetic male pattern balding. Be sure that he does not have any medical problems or is taking medications that have contributed to hair loss.