Before revision:  The factors governing the structure of the obtained network, such as the dependency of friendship upon distance and age composition , are thoroughly studied through extensive simulations focused on three Italian cities of different size.
After revision:  While household links are entirely data-driven, we propose a parametric probabilistic model for friendship, based on the assumption that distances and age differences play a role, and that not all individuals are equally sociable. The demographic and geographic factors governing the structure of the obtained network, such as the dependency of friendship upon distance and age composition , are thoroughly studied through extensive simulations focused on three Italian cities of different size.