I have it and so does my son. You're right, it's inherited and has nothing at all to do with weight. Talk about doctors blaming everything on weight! Sheesh.
I imagine you found out that the tiny bumps around your hair follicles get red and inflamed. My KP got better as I got older, into my 30's. DS has a bad case and uses skin products with glycolic and salicylic acids that help a lot. Here's a link to an online store that sells KP products and has some good info on how to treat it:
http://www.dermstore.com/profile_Ker...ris_400060.htm His dermatologist recommended the AmLactin cream listed on the page.
Good luck! We've found that treating it with the right skin products can really make a difference.