TRIGGER WARNING: Ethnographical content/eugenics.
Very TLDR: We cannot avoid thinking about both our genuine racial differences, and constraints on the people who will use gene editing to someday breed "demi-humans."
One of the least 'ethical' experiments by the standards of modern society that I've always wondered about would be some theoretical dictator who had absolute control over human breeding patterns. Over time, you might be able to identify and selectively breed exceptional/useful genetics across multiple discrete populations. In essence, treat humans in the same dispassionate way one might if one needed to breed a dog specifically to herd sheep, or (more frivolous but just as likely) to have a big, fluffy coat.
How long would it take to make the tallest human? To isolate an exact Pantone shade of skin? A certain musculature or proportional ratio? Capability in mathematics, or sociableness, or creativity?
Sooner than we think, we will have the ability to perform these tasks across decades, rather than millennia, and perhaps even faster.
Before we have this power in our hands, it is imperative that we change our attitudes about the differences between our human races.
Speaking with historical context, there are no doubt parties who would, without qualms, filch the height from the Dutch, the endurance capacity from the Kalenjin, the purported genius from the Ashkenazim, the musical ear from the Han. And they will do so with a mind towards profit, and few or no regulations that would dictate some compensation to the peoples whose very genes they will copy-paste wholesale into a hopeful race of demi-humans.
When we can tinker with genes, we will. There is no doubting this. The only current prohibitions are focused on safety as we take fledgling steps into warping humanity on command. We can either embrace our differences and respect that we are close to being handed keys that are normally kept in God's pocket (so to speak), and realize that we must solve our baser problems first.
The difficulty with this is that we must accept which stereotypes about ourselves may actually be true, even partially. Do certain races exhibit greater athletic ability? Greater intellect? Greater self-control?
We have killed millions of people across the ages because we were incapable of maturity in dealing with peoples of different languages, skin colors, heights, facial structures.
What will we do the knowledge that we are, in fact, different from one another? How can we handle knowing ourselves more fully?
Is it our responsibility to tamper as little as possible, only where medically necessary? Or will we create entire new breeds of humanity with new bone structures, melanin configurations? Will we tinker with brainpower, resolve, even tendencies towards violence or humor... once we are able to do so?
With the tools that genetics may offer in the not-so-distant future, the rich will of course have access to these tools first, to make their children taller, smarter, stronger (and without large-scale societal changes, likely paler).
Even if I weren't personally intrigued by the idea, it is certain to happen, if and once we have that power, we need to have thought about how we could use it well, and the many ways in which it could go horribly wrong.
And we need to accept that there are real, significant differences among us.
Before we arrive there, we've got a lot of growing up to do.
Bonus Thought: If someone asked you, "How many of ((your nationality/race)) should exist, proportional to all humans?" Our instinctive answer "More of us, not less of us" is the primal urge that underpins all great atrocity.
More of me, less of them: and some line to draw on which of "us" is which.