Most fantasy works, however outlandish or alien the setting, accept the standard customs for legalising the relationships between sexual partners and taking care of children. Marriage is (mostly) for life, is between one man and one woman, sex outside that pairing is frowned upon, children born outside that pairing are a matter for social disapprobation, prostitution is immoral and usually illegal. These attitudes, although drifting into a more liberal version in many countries, are still so prevalent in all modern cultures as to be virtually ubiquitous.