Depends on the definition of "moving out".
When I was 18 I moved to my own apartment at the same house as my mother still lives in. (Paid rent and had separate entrance, kitchen, bath, the works.) So that's when I moved out.
At 26 I bought an apartment (with my girlfriend) elsewhere and moved away.
Now, at 38, after a few other moves around Bergen, I'm in the process of moving back into the house I grew up in, ironically the same apartment I moved out of 12 years ago, so you might say I'm moving back home. 🙂
Now the 4 apartment house is going to be inhabited of 1) My mother and her boyfriend 2) My 93 year old grandmother 3) My brother and his extended family and 4) My girlfrend and I. Could be troublesome, but mostly nice, I guess... 😉