Nope, not actual son lol..
Couple years ago Mason acted (well, not literally acting since he's just a couple months old back then haha) as JGS' son for a movie called "Baby and I"..
Can't believe he has grown up super fast and super well..
Many have been calling him "The Next Nichkhun" for his good looks haha..
I hope he'll grow up even more handsome than Nichkhun ;p