Troubleshooting relationship ACL Permissions
Did you follow the recipe at: https://civicrm.org/blog/sarahgladstone/recipe-for-handling-youth-registration-with-civicrm

Make sure you have both extensions: 

Entity Settings Helper Extension (nz.co.fuzion.entitysetting) version 1.2

Related Permissions Extension (nz.co.fuzion.relatedpermissions) version 1.2