You may deny an occupancy of two parents and a child over 6 months. This will not violate the law. If you rent to a single parent with a child, an unemployed deadbeat boyfriend from prison will be waiting in the wings to move in as soon as you get out of sight. Unmarried couples seldom live out the lease and will leave owing you money. An online service like publicdata.com is inexpensive and will tell you if a couple is actually married, what civil suits action has been taken against them and will provide you with a criminal record if one exist. One clue a couple is not married is different names on the driver's license. Be sure make a scan of them with the application so you get their real names.