Have a heart to heart with them. Do it early in the trip so it doesn't build. I always took it as a compliment when people would comment (not so much anymore, unfortunately lol) but I wouldn't take **** from my flying partner if they kept treating me like that.

Flying with people twice your age can be tough but honestly the vast majority always treated me well and part of the team and were happy I was there. I will say some of the naazi's are insufferable and thankfully they will be gone soon.