keep it in the family
(v.) To bear children formed out of incestous relationships.
That guy fucks his sister because he likes to keep it in the family, and wants kids with her.
keeping it in the family
Partaking in incest
“Why do so many people in this town have the same last name? Are they keeping it in the family or what?”
keeping it in the family
Keeping it in the family is when a girl or guy dates someone, breaks up with that person, and subsequently dates someone related to the first person. Keeping it in the family originates from an expression that involves not letting an issue out of the borders of family knowledge, and so by dating someone else in the family, the subject is "keeping it in the family".
Reid : Man Karlson, isn't it weird that after you rejected her, morgan went for your brother?
Karlson : No way man, she's just keeping it in the family.
Karlson : No way man, she's just keeping it in the family.