I worked at a company where the Director had most of his family also working there at one time or another and it was awful.
His dad was basically given a busy work role, and I quite liked him but it was disruptive to have him come and go.
Part of his job was to drive the directors ex in to do her role, she came in late and left early and lorded it over everyone while she was there.
She left for reasons we were never told but his new partner arrived in the same role almost immediately. I liked her, but again she was in late and out early and some days not there at all.
In both cases, I was the one left to pick up their work when they weren't about. I was on half what they were being paid but did the bulk of the work.
He also had siblings work there, one of his older kids came in for a bit, even his mum arrived for a short time.
The other director didn't bring any family in but he did have many affairs and always with people who thought that sleeping with him conferred some of his job title over to them, so that was always a nightmare. His long-term mistress once refused to let me do a training course I needed even though she had fuck all to do with training or recruitment.
It was a horrible place to work. The main director prided himself on his self-made, professional image but it was the most disorganised and unprofessional place going.
As a previous poster has said, no matter how bad the family members performed, they were family and loyalties always lie with them in the end. I was miserable in that role by the time I left, and it knocked my confidence at work for a long time after.