Taking a broader approach, a 2017 paper by Jan Havlíček and colleagues assessed men's preferences for both the size and shape of women's breasts in four cultures—Brazil, Cameroon, the Czech Republic, and Namibia.
It can all get quite confusing.
This difference might allow men to assess female reproductive potential.
Have you ever hear of a guy telling a flat chested girl to put her top back on because her boobs are too small? That includes boobs, butts, and your weird eyebrows.