Using genotypes to predict phenotypes is a coming activity that will only increase. In the past, traits that were assumed to be genetic were used to commit all sorts of offenses, minor or major, to the independence or well-being of individuals, and groups were targeted--assuming that individuals bore the traits assigned to their group.
This was the eugenics era and these measures were justified on darwinian and social grounds that the unfit were not worthy to live as 'normal' or 'fit' people do. The current era of genetic determinism does not seem likely to lead to mass executions the way the twisting of eugenics did in the 20th century. But what forms it will take, and the degree to which genetic information is used is probably unpredictable.
Whether it will be institutional (government policy, insurance or employment structures, etc., that are based on genotype), or whether it will be implemented by individuals, only time will tell. Clearly however, parents will be using such information in regard to their reproductive patterns--a matter of individual 'eugenics'. That is already happening.
If parents who carry dangerous mutations abort or prevent the birth of offspring with serious impairing disease, is this good for society? Here, we do not deal with the question of whether such persons deserve life or should be viewed as defective, any more than those of us who, say, wear glasses or are born with deafness are.
One subtle point was once known to all geneticists, but may have been forgotten, depending on how genetically-based abortion or in vitro fertilization (IVF) programs are carried out. It is called reproductive compensation, and it goes like this:
Remember yesterday's post, where we discussed a gene with a normal D allele and a recessive disease allele, d. Let's say that dd individuals have the disease and can't reproduce, so the source of the allele in the population are the Dd 'carriers' of the harmful allele. If screening is done to detect dd fetuses, which are aborted, then no more cases of disease will be produced. This would also prevent those two copies of the 'd' allele from being present in the next generation. Two Dd parents will produce 1/4 dd offspring, so a lot of 'd's will disappear in a single generation of screening, a rapid form of beneficial artificial selection.
But if the screening accepts Dd offspring, rather than aborting them, there will continue to be carriers in the population. Reproductive compensation occurs if parents selectively remove 1/4 of their offspring but, because they can do this kind of testing and prevention, allow the birth of more Dd carriers. In this case, the frequency of the 'd' allele can actually increase in the next generation, causing an excess production of carrier children by parents jubilant that they won't bear diseased children. In the long run, unless the screening program is always maintained, there can be an increase of disease at some point in the future. If we're doing this to countless of genes for which we develop screening tests, the total risk of such offspring could increase greatly. How serious this problem is, is a legitimate question. It was one that was discussed in the eugenics era and even afterward.
We don't happen to know how such screening programs handle the Dd conceptions. But if screening removes or prevents the birth of Dd as well as dd children then a true (and rapid) reduction of harmful alleles will occur. IVF might automatically do this, but if for people who can't afford or are not aware of the fancier and costlier technology rely on abortion, they would have to abort 3/4 of all their fetuses to prevent new copies of 'd' in their offspring, which they are most unlikely to do! This would mean an advantage for the wealthy and privileged....not exactly a new phenomenon.
A second issue is what the societal impact would be if, say, everyone decided to genetically engineer children to be good baseball players, or good guitarists (or fearless soldiers, or intelligent investors, or mathematicians). To each parent this may seem a good goal, but in society at large, it would likely be a case of the endless evolutionary rat race. All those brilliant mathematicians would not be particularly brilliant in the eyes of society. There will still only be so many jobs in math departments.
Instead, in a society of mathematicians there would simply evolve some new way of competing for resources and success. If there are too many born with Olympic sprinter genes, of course they can't all be on the Olympic team, or the Olympics would have to change. Or we'd just get bored with sprints. Or the best times would simply decrease with a similar proportion of winners as we now have.
The point is that of unintended consequences. Evolution works with what's present. If I dream of producing an Isaac Newton, and nobody else does, I might have a successful genius whose Nobel Prize I can boast of. But if everybody produces Isaac Newtons, society will simply have to develop different criteria for its prizes. It would be like grade inflation: like Garrison Keillor's Lake Woebegone, all the children will be Nobel Prizewinners!
In this sense, eugenic dreams can be illusions, or almost certainly would be illusions.