It’s not a matter of it being unnatural, it’s a matter of it probably being doomed to failure. Evolution to a higher form involves some aspects of a species being accentuated and some aspects fading away. But there’s no way for us to know which aspects of humanity belong in each list, so any attempt to steer our own evolution is more likely to lead to our eventual demise than our ascendance to a higher level. In the end that might be natural, it might be our evolutionary destiny to screw ourselves into oblivion with a misplaced ego, and if eugencists ever take over it probably will be. The smart person who wants to help his species evolve does nothing directly towards that goal because we just don’t know enough to know what direction to steer in.