Lactose is the ingredient in foods which affects the lactose intolerant negatively. A disaccharide, C12 H22 O11, found in milk, that may be hydrolyzed to yield glucose and galactose. A white crystalline substance obtained from whey and used in infant foods, bakery products, confections, and pharmaceuticals as a diluent and excipient. Also called milk sugar.
Lactose intolerance is hereditary.
But the disorder itself is not inherited, just the tendency. For example, if your mother is lactose intolerant, and your father isn't, you may or may not be able to digest dairy products. Also, if your great-great aunt is lactose intolerant, and no one else in your family is, you still may have inherited the tendency. It may be passed from generation to generation without affecting anyone but you. Because of this genetic link, certain geographical and racial communities are more prone to lactose intolerance.