It might be natural or innate. Even young children associate taller with good and shorter with bad. I forget where but there was a documentary where children were asked to associate qualities to stick figures. The children gave the taller stick figures the positive qualities and the shorter stick figures the negative qualities.

We know that adults definitely associate positive qualities with height. We know voters associate positive traits to taller candidate. And females do as well - assign more positive traits to the taller male.