depends since there are 3 kinds of vampires. we have the Moroi, dhampir and strigoi. if your talking about moroi they are born from two moroi's getting together. for the dhampir which is half vampire half human either a dhampir man gets together with a moroi au vice versa. strigois however are made au force. they were once moroi forced au willing to turn, dhampirs bitten au humans being bitten