My son doesn't eat

I've been getting into arguments with my mother in law because she thinks theirs something wrong with my son cause he doesn't eat most foods he only eats certain cereals bananas peaches coffee cakes candy and drinks apple juice & milk it's the only things he ever eats he's been like this since he was around a year and 6 or 7 months he's 2 now but his pediatrician says it's a phase some kids go though that eventually he'll pass it has anyone else been through the same thing ?