The question was phrased ambiguously as "do men or women have more brothers." Here's three possible interpretations. One interpretation is "if I am the last bo

The question was phrased ambiguously as "do men or women have more brothers." Here's three possible interpretations. One interpretation is "if I am the last born (or some other gender-neutral specifier), do I have more brothers if I am a man or a woman?" As paulmd answers, the chances are even. But we can also interpret it at the aggregate level. Say we have a family with M men and W women, and we decide to count brothers by polling each person for how many brothers they have, and totaling the result up. If we poll men, we get M(M-1) brothers, and if we poll women, we get MW brothers. The result depends on the distribution, but at the expectation value (M = W), women have more. Same conclusion if we average instead of sum. The third, most natural interpretation is to "deduplicate:" ask each person to list his or her brothers, take the count of the union. This is the familiar sense: we would say there are three Brontë Sisters, even though none of them individually had three sisters. Here the number of brothers equals the number of men, except when then there's only one man; then each women has 1 brother and each man has 0.