In an open economy with common property resources at the community level, marriage and migratory decisions crucially depend on inheritance rules on the commons. Motivated by the traditional management of the commons in the Italian Alps, we present a model that fits the evolution of property rights observed over six centuries. Women's rights over the commons were progressively eroded from the Middle Ages until 1800, when there was an almost universal adoption of a patrilineal inheritance system. Communities switched from an egalitarian system to a patrilineal inheritance system in an attempt to protect the per capita endowment of common resources from outside immigration. The model shows that inheritance rules have clear-cut implications for marriage strategies, migratory flows, and fertility rates.