It's one thing if they're working and contributing to the household. It's another thing if they're just mooching off their parents.
But how do you know what the limits and expectations should be? Now there's a legal precedent.
A New York state couple has successfully sued their 30 year old son in what's being called the "Failure To Launch" case.
In court filings, his parents said they had tried for months to get their son to move out of their home. And yes, they put it in writing.
They left him at least 5 written notes over the course of several months... even offering to give him money and help him find a place to stay.
But he wouldn't budge. So his parents sued him and won (at least this round).
If you aren't familiar with "Failure To Launch" ... or if you just want an excuse to see Matthew McConaughey, here's the trailer for the 2006 movie--