Nature says don’t worry about “designer babies.” Not so fast, says Daniel MacArthur, a blogger at the excellent site Genetic Future:
[I]t’s safe to say that there will be no perfect baby. Instead, the prospective parents will face a tough choice between embryo A, who will likely be tall, slim, smart and cancer-free but have a higher-than-average chance of bipolar, early-onset dementia, and infertility; embryo B, who will be a little shorter, dark-haired, probably fairly gregarious, resistant to coronary artery disease, susceptible to bowel cancer, hypertension and early deafness; embryo C, who will be of average intelligence, unlikely to suffer premature baldness, prone to mild obesity and diabetes, but not at a high risk of any of the other major common diseases; and embryos D-N, who present a similar panel of competing probabilities.
…The parents-to-be will sit down together with dossiers listing a huge set of statistical predictions for each of their potential children, and make a decision as to which (if any) of these abstract collections of traits and risks they wish to bring into this world. Decisions don’t get much more emotionally traumatic than this: not only will they be making a decision that will shape their own lives and that of their future offspring, parents will carry a new, extra burden of responsibility for the fate of their children. If they decide on embryo A, and their child goes on to develop severe bipolar disease, they will carry the guilt of that decision in addition to the trauma of the disease itself.
That’s not to say that embryo selection is unworkable — in fact, I think it’s inevitable — but rather that this process is likely to require a degree of agonising trade-offs on the part of parents-to-be that is seldom fully appreciated. While I have no moral problem with the notion of embryo selection, part of me is glad that my child-bearing years are likely to be over before I have the chance to face this particular dilemma…