It's tempting to keep everything in the family. Your siblings will work for pennies, you can ignore child labor laws when you're hiring your own kids, and carpooling is a snap when everyone lives in the same house. Non-family employees, on the other hand, want things like stock options and a living wage. Ridiculous!
Sure, it may seem like a good idea to have an all-family staff, but hiring from outside is also vital. Your family members don't always have the perfect skill set, and someone has to be objective about the interests of the business (that is, their own economic interests) without letting emotions get in the way. It's also nice to have someone on staff who won't laugh if you try to fire him.