I would be ashamed to enjoy a standard of living significantly better than my parents'. I couldn't enjoy having steak if I knew my parents' grocery budget barely afforded them an occasional ground beef patty, couldn't enjoy a trip to Busch Gardens knowing that my parents' entertainment budget was limited to popcorn and Netflix.
But income doesn't tell the whole story. If I was making mortgage payments, car payments, student loan payments while they had no debts, I'd feel less obliged to help them. If I was struggling to acquire furniture and furnishings, to provide myself with wardrobe basics, while their home was fully furnished and they had more than enough clothes to last the rest of their lives, I'd feel less obliged to help them.
But if you can now afford to be very generous with them, to pick up the tab for shared restaurant meals, to bring over gifts of groceries when you visit, to surprise them with special treats, then do so. Most especially, give them opportunities to brag to their friends about how good their child is to them. If they don't seem to be struggling financially, this may be things like helping them with home upkeep and maintenance instead of buying stuff for them.