You’ve either said it or heard it: If you live in my house, you live by my rules. For whatever reason, 20% of young adults aged 25-24 live in multigenerational households, according to the Pew Research Center. As the kids move back, parents have a tendency to treat them the way they treated them when they were teenagers, says Sally Koslow, author of “Slouching Toward Adulthood.” “Some parents think of this as … a really cozy stroll down ‘Sesame Street.’ And the kids really don’t want to be with them, and so the parents are disappointed,” Koslow said. Financial boundaries are probably the most import lines to establish. Parents could have suffered setbacks in the economic downturn, too, but still feel obligated to help their child get back on their feet at risk to their own retirement savings.