I tell my kids what they should eat but they take no notice. That may be because they are married with kids of their own.
Seriously when they were young we only allowed sweets at the weekend and then rationed and for special occassions. They moaned but I notice that they have adopted the same policy with their children.
If there are sweets in the house, they are allowed to eat them just like anyone else. That said, we usually don't HAVE sweets in the house. My husband and I are both trying to lose weight and NONE of us needs all that sugar. We have been trying to have more fruit in the house.
I do make things like rice krispie treats, cookies, etc but I don't typically limit the kids unless I see them going crazy.