What is keratosis pilaris caused by?

Genetic condition: Keratosis pilaris (follicular keratosis) is a common, genetic follicular condition that causes rough bumps on the skin. It most often appears on the back and outer sides of the upper arms (lower arms can also be affected); also occur on the thighs, hands, and tops of legs, flanks, buttocks, or any body part except the palms or soles of feet.

Keratosis pilaris: Keratosis pilaris (kp, also follicular keratosis or chicken skin)is a common, autosomal dominant, genetic follicular condition that is manifested by the appearance of rough slightly red in color, bumps on the skin. It most often appears on the back and outer sides of the arm (though the forearm can also be affected), and can also occur on the thighs, hands, and tops of legs, sides, buttocks.