Sharon Duchesneau and Candace McCullough are a lesbian couple that also happen to be deaf. In 2001, they decided that they wanted to have a baby. Instead of going to a sperm bank, they approached a deaf friend for a donation of sperm. What they were hoping was that their child would be deaf. In December of that year, they had a baby boy, healthy in all respects, except that he had total hearing loss in one ear, and mostly deaf in the other ear. The parents couldn't be more happy.
Sharon and Candace wanted their child to be deaf so that he could be part of the community/culture that they belong to, the deaf community. Part of being fully accepted in the deaf community is being deaf. This isn't to say that the hearing cannot participate in this community, but they would never really be apart of it in the same way that a deaf person is.
Did they do anything wrong? It seems like that they brought into existence, purposely, a child that has a disability by most accounts. However, the deaf community doesn't view deafness as a disability. In fact, the very existence of the culture is under assault, or at least that's how many view it, because of cochlear implants that can help deaf children hear to a certain extent. Usually these children are not allowed to learn sign language, so that they can more fully develop their hearing and speaking abilities.
Imagine that you had a child, but the child that you had was not a normal child. Your child gave off a strange pheromone that most people would find quite unattractive, with the exception of a few people who could not smell it. The people who could not smell it also give off the same pheromone. Your child finds solace and community within this subset of people, but you can't stand going to social gatherings with these people, because as much as you love your child, the aroma is overpowering. You can tolerate your child's aroma, but only because there is one of her. A group would simply be too much. Would it sadden you to know that you will never be part of the community that your child finds significant solace in, that this community would be doing more to instill values and teaching her how to navigate through life than you as her parent would? If so, then perhaps you have an understanding of why Candace and Sharon wanted a deaf child.
This case has a lot of nuances to it. Whats a disability? Is designing a child like how Sharon and Candace did wrong? Was there harm done to the child?
On the other hand, would there be any significant difference if Sharon and Candace, after their perfectly hearing baby was born, simply put the baby's crib next to the stereo and played incredibly loud music to ensure that it would lose their hearing? (I think there would be.)