Differences in age preferences for mates can stem from partner availability, gender roles, and evolutionary mating strategies, and age preferences in sexual partners may vary cross-culturally. There are also social theories for age differences in relationships as well as suggested reasons for 'alternative' age-hypogamous relationships. Age-disparate relationships have been documented for most of recorded history and have been regarded with a wide range of attitudes dependent on sociocultural norms and legal systems.[1]