In improving human capabilities, should we deny ourselves free choice?

I am thinking of things like genetic engineering, study drugs, and sports doping. All these things help us improve our capabilities. Yet we choose to forgo some.

Some of the reasons that we, as a society, make it illegal to enhance our capabilities is that we think it makes it unfair (in sports) or it might harm the individual.

If you make something that improves performance illegal, you then have to enforce your will. You enter a cat and mouse game where people are trying to get an advantage using a technique you can’t catch, and you try to develop ways of catching those techniques. If you let people use any technique, then all athletes would have a choice, and wouldn’t be punished for their choice.

However, should we let people choose to harm themselves? If so, why are some harms allowable, but others not? Why is doping illegal, but playing football (American) or boxing is not? Why is genetic improvement by selecting a mate considered allowable, but manipulating genes more precisely is worrisome? Why do we make drugs that allow us to study better and do better on tests illegal? Should we continue to discriminate against some capability-enhancing techniques, or should all be fair in maximizing our abilities?