In ancient Rome, adoption of boys was a fairly common procedure, particularly in the upper senatorial class. The need for a male heir and the expense of raising children and the Roman inheritance rules (Falcidia lex) strictly demanding legitimes were strong incentives to have at least one son, but not too many children. Adoption, the obvious solution, also served to cement ties between families, thus fostering and reinforcing alliances. Adoption of girls, however, was much less common.