You are quite right that a lot of harm could be done by the simple minded application of genetic technology. No doubt mistakes will be made. This is the sort of thing that commonly happens with new advances in technology. It is the rare child who learns to skate without getting skinned knees! But it's worth it. That's the point.

Geneticists are well aware of these problems. A possible danger of widespread gene splicing might be the elimination of some gene or genes from the pool which, although often associated with some undesirable condition or behavior, also had more or less hidden, perhaps subtle, benefits. One plan is never to eliminate any gene completely. Rejected genes can be saved and if it is later found that they have a use they can be reintroduced, perhaps with suitable modification or with the support of other genes which will bring out the good and suppress the bad effects.