Male Baldness Info

He’s an 8 month old moggy/Burmese cross, and according to the vet he’s completely healthy. Ever since I got him as a young kitten, he’s had no fur from the base of his ears down to his upper eyelids- so he has 2 triangle-shaped bald patches on his face. Recently I’ve noticed the fur on his nose & between his eyes is thinning, and he has little bald patches on his chin. The fur everywhere else is normal and healthy. I thought at first that the baldness seemed to be ‘spreading’ because he must be losing fur in fights, but I guess if he was fighting, he’d be getting injured, and he hasn’t been.There doesn’t seem to be anything wrong with his skin in the bald patches (it’s pale white, just like the rest of him).
So does anyone know why my cat appears to have male pattern baldness??