It may be behavioural and leaving as it is for now and thinking that it will change with time or can be changed it later can something serious. My little brother had similar issues and he was left alone and feeding him just the things he liked. Later on as he grew his eating became disorderly. He got so addicted to similar type of food and didn't try out normal food and he started to put on a lot of weight and his health grew bad. My parents looked for many solutions and at last they've decided for any counselling and got him to Bellwood Health Services, Toronto. I am not mentioning this to scare the parents here but just to make them aware that don't make excuses not to feed children the food they need to have at this age. Believe me it is hard to get rid of bad habits.