The Campbell Collaboration, after reviewing more than 100 studies involving more than 666,000 children, has concluded that placing abused children into foster care with relatives results in fewer mental health issues with the children, fewer behavioural problems and fewer placement problems than similar children in foster placements with non-relatives
There were no differences in the rates of reunification with parents. Children placed with non-relatives were more likely to be adopted while those with relatives were more likely to be in guardianship arrangements. The review concluded that placing abused children with relatives appears to be a viable option, but cautioned that it is difficult to evaluate this kind of issue, and that many of the studies did have vulnerable methodologies.
Kinship Care for the Safety, Permanency, and Well-being of Children Removed From the Home for Maltreatment:A Systematic Review, by Winokur, Holtan, Batchelder, 03/03/2014, http://www.campbellcollaboration.org/lib/project/51/