Cousin marriage is common worldwide but ranges wildly from a small percentage of all marriages to 40-50% in some regions of Pakistan. Populations differ not only in rates of cousin marriage, but also in which relatives they permit as spouses, distinguishing maternal from paternal kin and parallel from cross-cousins. Marrying a father’s brother’s daughter (FBD) is of particular interest because it occurs at especially high rates where it is preferred. Two hypotheses have been proposed: the female inheritance hypothesis, which posits that FBD marriage prevents wealth escape when women inherit, and the clan solidarity hypothesis, which posits that it strengthens patrilineal kin groups by increasing relatedness. The female inheritance hypothesis has been linked to Islam, which introduced inheritance rights for women and might explain why cousin marriage is particularly sticky amongst Muslim populations. Both hypotheses rest on the assumption that father’s brother’s daughter marriage consolidates wealth or relatedness better than other cousin unions, an assumption that is not obviously true, since wealth can return through in marrying daughters, and cross-cousins are equally related. I test these two hypotheses by simulating how different cousin marriage types affect wealth escape and within-lineage relatedness under varying inheritance rules.