I buy the sugary childrens cereals all the time however its me who eats them, the children are still happy with weetabix and corn flakes. I'm a mean parent
I ate biscuits as a kid for breakfast with a cup of tea.
It was either that for my mum and dad or I wouldn't eat anything as I wasn't 'hungry'.
I had a normal packed lunch consisting of a sandwich (usually ham or chicken - sometimes cheese), bag of crisps, banana and a small chocolate treat (I.e. A mini roll or a breakaway etc.) then for dinner I had something like birds eye chicken fillets with jacket potato and peas followed by a yogurt. I Usually had a chocolate bar or piece of cake as soon as I got home from school as well.
Although a pretty shitty diet when you think about it i did exercise a lot and could have been a lot worse as kids diets go. I Played football all the time, sometimes at lunch when not raining and rode my bike a lot after school in summer. I wasn't obese, fat and still aren't but I don't eat like that now.
In my opinion, everything in moderation as a kid. Much the same as when you're an adult. If they have sugary breakfasts just try and get some okish carbs in them later in the day with protein. I learnt about nutrition properly when I started doing weights at college. Until then it's just about getting your kid to that stage in life without becoming fat and giving them diabetes.