In NewScientist (8 July 2017, paywall), Frank Swain gives an overview of the question of whether or not it would be ethical to force everyone to adhere to some definition of normalcy, enforced through medical means. Frank gives the a posteriori answer:
Perhaps conformity isn’t as good for society as we suppose. In 2015, psychologist Jesse Harrington at the University of Maryland published a study showing that highly restrictive societies fared worse in measures of overall happiness, rates of depression and suicide than moderate ones – but then again, so did highly permissive cultures. When it comes to how much abnormality we should tolerate, then, it seems we would be best off having the normal amount.
I think the a priori answer should also be no, based on evolutionary requirements. It’s only through endless variety are we likely to improve our survival capabilities in the current and changing environments. And that last clause brings up the important point that if we define normal as the optimal condition for the current environment, what happens when (not if!) the environment changes? Chances are that the current optimal condition will not be optimal for the new environment – and that the pressure to evolve to the next optimal condition will be too great, resulting in the elimination of most of humanity.
Non-conformity is the general winning long-term strategy.
