Counterpoint: traits arise through neural networks established in the brain. What's to say that we won't reach a point where such traits can be artificially engineered?
Likely not in the near future, but I see it happening hundreds of years from now.
Great. Now we only need to decide which traits are those...
Perhaps servility and humility. Doing what's told? I bet lot of moms and dictators would love that.
Eternal happiness. Why shower, when you are happy as you are? Why eat when you are already happy?
EDIT: The point is, our traits depend on environment. If it changes, we change as well. We might think we control our environment, but so far, I doubt that's possible.
Likely not in the near future, but I see it happening hundreds of years from now.