This is a polite way of saying that he had sex with his aunt. Some languages use more direct phrases such as "had sex with." (See: [[rc://en/ta/man/translate/figs-euphemism]])
The idiom "carry your own guilt" means "you are responsible for your own sin." AT: "You are responsible for your sin" or "I will punish you" (See: [[rc://en/ta/man/translate/figs-idiom]])