I have written many times about people breeding dogs for intentional defect: brachycephalic dogs that can barely breathe, dogs with coat colors and patterns that lead to deafness, dogs with such sagging skin they are beset with perpetual infections.
But people do not just breed dogs for defect. Sometimes, they also breed their own children for defect. From The New York Times:
Yet Susannah A. Baruch and colleagues at the Genetics and Public Policy Center at Johns Hopkins University recently surveyed 190 American P.G.D. clinics, and found that 3 percent reported having intentionally used P.G.D. “to select an embryo for the presence of a disability. In other words, some parents had the painful and expensive fertility procedure for the express purpose of having children with a defective gene. It turns out that some mothers and fathers don’t view certain genetic conditions as disabilities but as a way to enter into a rich, shared culture.Later in the article, a deaf mom wants a deaf child, and a dwarf mom wants dwarf children:
Barbara Spiegel, a homemaker in Maine who has dwarfism, had a first pregnancy that ended in miscarriage. She underwent genetic testing during her second pregnancy, and because of a laboratory mix-up involving petri dishes, was told that her child would grow to normal height. She would have loved the child, she said, but in an interview, she recalled thinking, “What is life going to be like for her, when her parents are different than she is?The good news is that most doctors find the use of preimplantation genetic diagnosis in order to "select for defect" abhorrent and are not willing to do it.
At the Kennel Club, however, the breeding of the broken, the deformed, the diseased, and the dysfunctional continues as a positive selection bias, and not a rare one.