the things that he did on that day. >> reporter: brendan reegan is following in the footsteps of his firefighter father robert, who was killed answering the call on 9/11. >> throughout the process, it's definitely brought me closer to my dad, and as that happened, it only made me want to do the job more and more. >> reporter: 21 of today's graduates are children of men who died in the line of duty 13 of them lost their dads on 9/11, including greg kumpel. >> i think he would be surprised. because i wanted to play baseball growing up, and my brother was always the one that was his little shadow. >> reporter: six have seen their fathers pass away from illnesses linked to their time at ground zero robert telarsio jr.'s dad died of brain cancer two years ago. >> i'm making my dad proud. definitely something he always wanted me to do. >> reporter: these 21 firefighters say they're like family now. >> they are honoring their fallen loved ones they are continuing their family's legacy