I wonder what laws, if any, there would have been around incest at the time?
Roman law prohibited marriages between close kin, whether by blood and by marriage, which the Christian emperors of the 4th and 5th centuries expanded upon. None of these laws, however, went as far as legalists in later centuries would. The
Responsa Gregorii, attributed to Pope Gregory I, prohibited marriage to anyone within seven degrees of kinship. In other words, one couldn’t marry anyone closer than one’s seventh cousin. It also forbade intercourse (or marriage) with the blood kin of one’s (former) spouse. Merovingian law shared these prohibitions, but took things a step farther, banning marriage between godparents and any member of their godchild’s family as well.