I think you're mixing up the fact of outlier (subgroups) with the location of the mean in a normal distribution. Looking at the pictures in question it does see

I think you're mixing up the fact of outlier (subgroups) with the location of the mean in a normal distribution. Looking at the pictures in question it does seem to me that GP has a point, i.e. BMI could be a simple proxy for what the NN is detecting as sexual preference.