In order to be valid, instruments must be uncorrelated with the error term in the explanatory equation and have no direct effect on female (male) migration. To be relevant, the instrument must be correlated with the endogenous independent variables, that is the SIGI. Previous studies on gender inequality rarely shed light on the possibility of endogeneity issues and the validity of the instruments to solve them. A prominent exception is represented by Dollar and Gatti (1999), who instrument gender inequality in a growth equation by religious affiliation and civil liberties.