That's a simple question with a complex answer. The vast majority of men "inherit" baldness (the medical term is androgenetic alopecia), so if your father / grandfather were bald, you're fighting an uphill battle. Diet, stress and certain diseases can also cause baldness, as can certain drugs and medical treatments.
Buy yourself REAL "Ghost Gold" or mono-atomic gold. 1.5 grams a day...and will NEVER age...I'm 29..but look 21...I grew my hair back (no receding line anymore at all), my hearing grows sharper everyday, my eyes too! There are SOOO many benefits. I don't feel like writing a book on it...just find some on EBAY. make sure it's real though...not just ORMUS material...but ORMUS GOLD