"At every tier of educational attainment men earn more than women"?

I remember hearing this in Sociology. Could the fact that males are much more likely to major in something like Engineering while majors like Communications are almost exclusively female have something to do with it? Even with just a high school diploma, or vocational certificate, could the fact that a man is much more likely to learn how to weld as opposed to getting a certificate in cosmetology play a part? What do you think?