Medical Genetics When comparing height differences between men and women women are, on average, 3 inches shorter. a woman with a certain number of" genes will be, on average 3 inches shorter than a man with the same number. when that difference is taken into account there is no selective bias in matings for tallness in human populations.Medical Genetics When comparing height differences between men and women, women are, on average, 3 inches shorter. A woman with a certain number of "tall" genes will be, on average, 3 inches shorter than a man with the same number. When that difference is taken into account, there is no selective bias in matings for tallness in human populations