Unless "nepotism" violates the terms of an employment contract or union agreement, it is legal. Additionally, giving a family member preference in hiring is perfectly permissable under the law unless it is also based on some form of legally actionable discrimination (i.e. race, relgion, age (over 40), diability, etc.). Bottom line most employment is "at will" which means that an employer can set the conditions of the worklace much as it sees fit.