According to Satoshi Kanazawa in Psychology Today, men on average are slightly smarter than women. This difference does not emerge until after puberty, however; girls mature faster than boys and prior to puberty are actually, on average, more intelligent than boys. Studies suggest that the shift occurs somewhere around the age of sixteen.
Although men on average have a slightly higher IQ than woman, the difference is related to height rather than sex. People who are taller are, on average, more intelligent than shorter people. Men typically are taller than women and therefore have slightly higher average IQ scores when compared to women. In studies that control for differences in height, women are actually slightly more intelligent than men.