It won't happen explicitly of course. The root comment mentioned "depression", for example, which is at least in part caused by inadequate work-life balance, poor quality of life in general, lack of social fabric, etc... So if you would genetically engineer people to be less depressed, even if you just empirically looked at what genes depressed people have in today's world (as the root comment is proposing), you could end up engineering people that are OK with working long hours for little pay, eating slop, sitting at home doing nothing, never socializing with anyone, obedient to their boss, etcetera etcetera. This would be, in effect, "genetically engineering an under-class", yet it would be easy to defend in the newspapers by just saying "we're only getting rid of depression, how can you be against it?" It's just a logical conclusion if you can think more than two steps ahead.