Nurture implies a possibility of change, nature is m ore fixed-and how the weight assigned to one factor or the other varies with the specific behaviour being explained. Biology and social effects affect the gender gap (i. e. , the likelihood of a man outliving a woman and vice versa) Gender imbalances in postsecondary education are well documented. Female students are overrepresented in the humanities and social sciences while male students are the majority in mathematics, technology and sciences. Growing gender differences in literacy: some think that the greater physical activity among boys (biological factor?) discourages parents from reading to them as often as they do to girls (a social factor). Girls told that they may not do well on a math test actually do less well, while boys given the same message do better, perhaps in an i"ll show you fashion. Positive expectations thus may be ever more important for girls than for boys.