One possible confounding variable that immediately lept to my mind was a study published sometime in the past couple years indicated that women's preferences ch

One possible confounding variable that immediately lept to my mind was a study published sometime in the past couple years indicated that women's preferences change depending on whether they are currently taking hormonal birth control. I believe it did say that more "feminine" characteristics were more attractive when taking such birth control - and these birth control methods are probably more common in countries with better medical systems in general.