I had and to some extent still have the same problem with DS - 3.5yrs. He eats varied foods in the nursery but if I cook the same for him at home, he freaks out.
The amount of food I have chucked out is unreal and I was in tears at him not trying anything. Then I thought right, he's eating varied stuff at nursery, he eats yoghurt and fruit so its not as if he's missing out on any nutrients. If he wants cheesy pasta for dinner each night, he can have it! I always added some veg on the side though - which he sometimes ate, sometimes not.
Cheesy pasta is the main dish for him still, but I've managed to get him to eat fish by putting it on the side of the pasta. As he likes cheese so much, I tried him with cheesy omlette and cheesy jacket potato and I think we are making headway.
One thing I've found though, is that sometimes, when I've put something new in front of him, he's created and I've said don't eat it then and then half an hour later he's gone back to it and tried it.
If however, he flatly refuses, I will offer him a yoghurt or fruit salad (no chocolate) and he sometimes eats that, sometimes not
Its very stressful and I do appreciate your worry but I don't think will do him any harm