Don't let these guys get you nervous. Your hair is very thick otherwise and you have no signs of temple recession.... at your age it is completely normal to develp a "mature hairline". Yes, this is still caused by DHT, but does not necessarily mean you are heading into full fledged male pattern baldness. Many, many men develop a mature hairline in their 20's and it stays that way for years. I would see a dermatologist specializing in hairloss who can look at your scalp and determine if miniaturization is occuring elsewhere such as the top or crown...if so then, yes I would probably consider propecia as a preventative measure. For right now, I would definitely not worry as much as these guys would have you....and finasteride is not your only hope at the moment....you may not even have a problem. I think too many young guys in your situation start to panic and jump on finasteride when it probably isn't needed.....and it seems to me, these are the same ones that constantly complain of excessive shedding and sexual side effects and then post pictures of themselves with a head of hair most here would kill for.