Whether moral choices are natural is neither here no there from the moral perspective. That would be a biological or sociological matter. In any case, to say they're "natural" for people is misleading, since personhood itself is unnatural in the animal kingdom.

That would be like saying miracles are natural or normal for God. Yeah, but God would transcend the norms of nature. Likewise, people act anti-naturally as a matter of course (because of our self-awareness, reason, imagination, and cultural idealism); that's the existential revolt against the absurdity of the "given," prehumanized world.

Morality is about making the real world conform to ideals, and there's usually a gulf between the two because nature is amoral and indifferent to the plight of the creatures that accidentally evolve within it.