Statistics on rape are common in western countries an are becoming more common throughout the world. They are, however, highly politicized, often sex biased, and have been accused of being unreliable because they are so diverse and are used by different groups for different reasons. This is partly because of inconsistent definitions of rape in both legislative and academic studies. However, it is also because of over reporting, under reporting and false reporting of the crime. In the United States rape is defined differently by separate states. In many legislatures in the world some non-consensual sexual acts are not defined as rape at all. They may be considered legal, or as an illegal form of sexual assault. In some jurisdictions, male-female rape is the only form of rape considered rape while in others male-male, female-male or female-female rape may also be included as a legal form of rape. Rape of children is rarely reported in official reports. Nor is the rape of children by their mothers and fathers or other relations represented in official publications. Rape, alone among other major crimes, suffers from severe definitional contradictions that create controversial statistical disparities.