Is it appropriate for a PI to appoint someone who is a family member? I am a junior faculty in one of the top-tier research US institutions. I just joined the department and hired two GRAs meanwhile. In addition, I would like to appoint one more individual in my research group who could be appointed as a research engineer/technician. His/her role would be to support my research program and assist my GRAs on their PhD work. I am wondering whether there are any legal issues/conflict of interests if he/she is one of my family members. How will the department see this recruitment?
The rules differ from country to country, university to university, and department to department. 

On a practical note, I would not want to be in a supervisory role towards a family member. In that role I need to be able to make unpleasant decisions, like tell someone if (s)he did a bad job, handle complaints, or even discontinue employment. That is hard enough as is, but if it involves a family member...