Just wanna vent about the grandparents

Unfortunately have been living with my inlaws for the past 4 years (its common in my culture). My child is 3, so he grew up with them. BLW was going so well and he’d eat everything, all the veggies. Then grandparents taught him to eat junk- ice cream, jelly, sweets, donuts. And now he wont eat anything else. If only they’d never introduce all that crap to him.