Family Photo Hailey, left, and Jacob Knowlton pose for a family photo with their sister after Hailey’s graduation from Marine Corps boot camp at Marine Corps Recruit Depot Parris Island, S.C. Jacob and Hailey are twins and serve together in the Marine Corps. SHARE IMAGE: Download Image: Small (71.68 KB)| Medium (122.88 KB)| Full Size (0.7 MB) Tags: Marine Corps Photo By: Marine Corps Staff Sgt. Jennifer Martinez VIRIN: 190124-D-KY377-0002.JPG Photo Gallery