'll let my mom post on this. But i'll put my two cents in as well:
I was allowed to live at home (or at college) after age 18 as long as I was in school. My parents paid for me to live on campus in college.
The day after I received my bachelors degree, however, I was on my own. I was to have a job (even if it was at McDonald's) and support myself. I could live at home, but I would be paying rent.
Since January 1, 2004, at age 22, I was living on my own. Paying 100% of my own bills, including medical expenses, rent, food, etc.
I'm sure if I were to become ill and unable to work, my parents would make an exception.
At first I thought my parents were being harsh - forcing me to have a job right out of school and making me have a huge sense of urgency to support myself. Now that I'm older, I look back and I see others whose parents didn't put that pressure on them. Guess what - they're still living at home, they don't have very good jobs (even though they have the potential), etc.
And it hasn't been without health problems - i was in the hospital for IV antibiotics twice in 2005 and I had gallbladder surgery that same year.
So I am grateful for my parents pushing me. I know many CF parents baby their children and I'm grateful that my parents decided to raise me just like any other child.