I haven't because I'm passed the point of caring about hair....it's non issue for me now. But I don't see how he can disagree that it's genetic when you can clearly see MPB passed down from father to son, etc. My grandfathers head is just like Dad's and mine is just like his. It's clear to see that it's in the gene pool. And on the flip side, guys that have full heads of hair pass those genes on to their sons etc. Very clear. Not sure what their is to disagree with.
Even if there was something you could do about it, you still have the genes to have MPB meaning if you just go about your life, those genes are going to express themselves.