This is probably the only way "humans" are going to colonize any planets other than Earth. And probably lots of new places on Earth too.
Just include the genes for extreme-cold or extreme-arid climates. Or the genes for low oxygen environments, or even for metabolizing useful things from eating rocks. Or from spending 24 hours a day in salt water.
Is there a gene to avoid getting addicted to doomscrolling? ;-)
There is no way it is just "just". And we should start from simpler stuff like vitamin B12, C and D.
Imagine if we could turn our bodies into perfect spheres, and then adjust genetic beauty preferences to match it.
Oh if only science was not constrained by ethics.
I can already see the people protesting against the creation of space marines.
The ease of this "just" is the most concerning thing in the context of humankind's survival.