so the title is a bit misleading. bear with me.
imagine if there were gyms where you can work out and can change any and every aspect of your physical body. be it weight, height, sex, complexion, race, everything physical (let me call all of them properties). If its part of your body, you can change it.
would people choose to be themselves in that world? how would that world be? do you think there would be racism in that world? do you think everyone will just try to be one or few of the types?
it would not be that straightforward. if you want to lose weight, you have to work out. have discipline and take care. same thing but for everything.
if you are truly happy with yourself, you would not want to physically change yourself. also if you are truly happy with yourself, you would want to change yourself because you want to be a better you. if you are not, and NO shame in that, you would definitely want to work on yourself. and of course, there will be a collection of people who would not go to these gyms for lot of different reasons.
are you happy with yourself partly because you can’t be anyone else?
It is certain that there will be a set of people who are accepted by the society as ideal. i am not arguing that that set has just one element. there will always be many in that set. then, everyone of the world will strive to be like those in the ideal set, provided everyone is motivated enough. everyone will work towards being their closest (assuming we can measure distance) person in that ideal set. with time, the total distinct properties (physical things which define a physical body) of people in the world will gradually reduce. ultimately, it is equal to the ideal set.
justifying that everyone in this world would go to this gym is a hard task.
Finding a mate is competitive. The motivation of being ideal acquires fresh support from this kind of pressure.
If a particular race is at a disadvantage, or taken advantage of, then each of that race can choose to change themselves to protect themselves. A race can also choose to protect themselves without doing so. Let me define race as a large loose cluster of people with similar properties. it would also depend on the kind of the threat a race is facing. If the threat is at a level of existence, then it is in complete interest of every individual to preserve themself by changing their properties.
Any individual may also feel new kinds of pressure exclusive to this world. For instance, in pursuit of optimizing workflows, capabilties, individuals may try to morph themselves to secure an improvement. this behavior is already present in our present world - doping. although it is unnatural and internal (not exactly physical) but it is just an example that there will exist the practise of changing properties (number of eyes, ears, hands, fingers, and so on).
of course, physical things of a physical body are just a small part of the entire world. there’s social class, social behavior, livelihood abilities, and so on - all of which do play an equally strong role, if not more. but everything physical would (1) almost be the same, OR (2) always try to be the same OR both.