There is a very famous case of twins who used dutasteride (1 twin went bald who didn't use dutasteride and the other kept his hair because he used dutasteride).
In your case, dutasteride worked well to prevent receding maybe but if your dad has hair into his 60s you have a genetic advantage.
Yeah but one of the twins didn't have a full head of hair if i remember right, he still had some hair loss even on dutasteride, because there is still scalp dht levels which dutasteride doesn't get rid of completely, just serum levels. Maybe im remembering wrong though.