My father has always said to me never work with relatives and the only time I worked in his office was when I had just left college and he was away on holiday for 6 weeks.
However, when I used to work for myself I did employ my sister for a while, she was inbetween jobs and I needed an additional member of staff. It was hard though living and working together, we had our ups and downs but eventually she moved away and now lives 200 miles away and we get on better than ever

A company I used to work for one of the Directors and his wife worked together and their relationship ended up in tatters due to working together.
I would never ever work with relatives again.
Also learnt a lesson of never work for friends to - used to have some really good friends, did alot of work for them and never got paid!!!!