Some parents choose to have genetic defects in their children:

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 . . .

. . . But a desire for children with genetic defects isn’t new. In 2002, for example, The Washington Post Magazine profiled Candace A. McCullough and Sharon M. Duchesneau, a lesbian and deaf couple from Maryland who both attended Gallaudet University and set out to have a deaf child by intentionally soliciting a deaf sperm donor.

“A hearing baby would be a blessing,” Ms. Duchesneau was quoted as saying. “A deaf baby would be a special blessing.”