I never did, but my 2 closest buds did, and it has it's ups and downs to say the least. One ended up getting fired by his own father (deservedly so), and the other quit so many times that I gave up counting. Things finally settled down when they reached their early 30's.

It is great to be able to know you will have a decent job with your parents, but you better be able to handle some criticism from those who love you. They certainly cannot show you any favoritism and will probably be tougher on you then a regular boss/co-worker.