Jojoba really doesnt reduce sebum production, but it is a chemical antithesis of it. Sebum has DHT molecules in it and can be reabsorbed back into the scalp for a fresh attack on your follicles. Eating alot of animal fats will increase the size of your sebaceous glands (glands that produce sebum, each and every hair follicle has one and an arrector pilli mucscle also). The post WWII Japanese now bald much more often than they used to, especially in the cities. Dermatologists there believe its because they eat pretty much like we do now, gooey hamburgers loaded with saturated fats from red meats and much less soy consumption, rice consumption, lower carbohydrates etc. Their sebaceous glands are larger, producing much more sebum, and its more full of DHT also.
Ive read that a peroxide in oxidized sebum (sebum gets rancid or spoils and oxidizes in the root sheath) has been implicated in dermal papilla cell death by some Japanese researchers. Its on one of these threads but I forgot which one, I think the new research and discoveries one. Im not saying "this is the cause of baldness" or anything, but it darn sure wouldnt help matters. I try to wipe my head with an absorbernt towel a couple of times a day and notice a film on it (sebum oil secretions) as I have oily skin (clear skin though|)..........hope this helps a bit.