I'm slowly making my way through the absolutely excellent Future of the Constitution series. The one I just finished was "Reproductive Rights and Reproductive Technology in 2030" and has the opening section:

"Larry, a paediatrician, and David, a wills lawyer, meet in their late 20s, fall in love, and marry on June 15, 2025 in Indianapolis. Three
years later they take in a foster child for eight months, and find the experience rewarding. By 2030, they are well-enough established in their careers to think about having their own child. Larry’s 24-year-old sister Marge has agreed to donate her eggs, and David will provide the sperm, so that each partner will have a genetic connection with the child. They work with an agency that matches couples with gestational surrogates, and settle on Janice, a 34-year-old nurse and mother of two, who is willing to help them in exchange for a $75,000 fee. In the process, Larry and David come to realize that they would prefer to have a male child that shares their sexual orientation. Reproductive cloning won’t do, the FDA hasn’t yet certified it as safe and effective. But gene studies show a strong correlation between five genes and sexual orientation in both males and females.

Larry and David discuss with their doctors the feasibility of screening the embryos they create with Marge’s eggs for male genes linked to
a homosexual orientation. The clinic doctors are experts in embryo screening and alteration, but cannot guarantee that the resulting embryos will in fact turn out to be homosexual. To increase the certainty, they will insert additional “gay gene” sequences in the embryos before they are placed in Janice. Embryos not used will be frozen for later use or for stem cell technology to create eggs from Larry’s skin cells so that the resulting child would be the genetic offspring of both Larry and David."

It then goes on to briefly discuss the ethics of sex selection of sperm and embryos as well as gene implantation – all for selective rather
than medical reasons. The author, a highly distinguished bio-ethicist, comes to the conclusion that prospective parents, such as Larry and David, have a 'right to procreate' and therefore anything that doesn't cause harm to others should be allowed in the objective to become fathers. He goes on to say that in his opinion genetic selection (or alteration) should be allowed as it is no different than giving the child the best after-birth care you can (e.g. good parenting).

The question for me lies in whether genes would be altered to remove a potential harm, for example cystic fibroses, or instead to attempt to create a 'good' – such as increased intelligence. In my opinion allowing choice of gender and orientation is a step too far. However, obviously this is a difficult topic. It reminds me of a similar thought experiment I read some time ago about a deaf couple wanting to select embryos to have a deaf child and whether this was wrong. If you say that it is creating an inferior child then what does that say about your opinion of the deaf parents?

Anyway I'm always interested in quandaries like this so if you know of any good sources of examples please let me know