A lot of companies don't allow family members to work for them because of a fear of nepotism or being accused of it. Even if you're working totally separate departments or divisions, there's always the possibility of somebody getting promoted or transferred to a position above a family member, and then it becomes a conflict of interest and bias because family members are less likely to hold each other to the same standards as other employees, be it picking them for promotion over other employees, not dishing out disciplinary actions if required, and so on.
