_John ROBERTSON _____+ | _David ROBERTSON ____| | | | |_Margaret CRICHTON __ | _William ROBERTSON __| | | | | _____________________ | | | | |_____________________| | | | |_____________________ | | |--William ROBERTSON | | _____________________ | | | _____________________| | | | | | |_____________________ | | |_Isabel PETRIE ______| | | _____________________ | | |_____________________| | |_____________________