Hypothetical Question — Propecia and Identical Twins

In response to “Propecia Benefits Won’t Last Forever?”

I understand this is a difficult question to answer but say two identical twins under same environmental conditions etc were losing their hair, one took propecia the other didn’t and continued indefinitely, would some time down the track (say 40 years) would they reach the same point of hair loss as each other or would their be lasting effects of propecia maintaining a substantial difference between the two?

I would guess that the twin taking Propecia will not lose the same amount of hair as the untreated twin, but that would depend upon the final pattern of the non-treated twin. The lower the Norwood balding pattern (see patterns here), I’d expect there to be less of a difference after 40 years, but the treated twin would have the benefits of maintaining his hair longer than his brother if he treated it in the early stages of the balding process. Good question!