Actually, white and male wasn’t part of the requirements, In the roman system every family had a vote, along with every tribe (Rome saw them as family), now commonly the leader of the family was a man who served in the roman army, and most commonly white because of where the Romans were, but the southern Rome had a few black (what we would consider sub-Saharan Africans) and many Arab families (tribes), it was also not uncommon for the wife to become head of the family if the men were in the legion or dead