Carrier

Hypohidrotic ectodermal dysplasia, or HED, is an inherited condition (from a damaged chromosome) that brings sparse hair, peg- or cone-shaped teeth, and the inability to sweat. This is because the defective chromosome damages the ecoderm, the embryonic layer that becomes skin, hair, and teeth. Mothers have only X chromosomes to give. Fathers can give an X for a girl (who then has two XX's and will use the undamaged one to build her ecoderm) and a Y for a boy, who has no choice but to use the damaged X since he has only one. So the women in Bonnie Rough's family lived with guilt each time they had a son.