Overcome the potential clash you may face learning how to parent despite your own parents... I call this "grand parenting". Knowing how and when it is appropriate to bring to your parents attention that things they are doing around YOUR children is unappreciated.
In our case we face donuts, among other things, but let's start with donuts. Eric and I try our best to limit the sugar intake throughout the day as Holden can be quite spunky without sugar. Give him a little sugar and you have a 3 year old monster on your hands. When the sugar packing starts at our regular Sunday dinners, it all seems okay because, hey, they don't have to be there for the crash. However, part of being a parent may be having these hard conversations with your own parents because it is in the best interest of your child.
Spinning the issue: Yes, it is a fact WE do not allow a bunch of sugars in our house. This is not a decision based only on our preference, but true facts of what sugar does to your adult body. Now, let's talk about sugar packing for a tiny human.
General consensus is that some children and adults are sugar-sensitive, meaning their behavior, attention span, and learning ability deteriorate in proportion to the amount of junk sugar they consume. This blurb encompasses all children, but our Holden falls into these circumstances: While studies show that activity levels go up in both hyperactive and normal children on high- sugar diets, the hyperactive children also become more aggressive. Now when we get home and Holden can't handle himself, how are we supposed to regulate this sugar induced monster? It is important to lead with education and general concern for your child's well-being because your parents likely want the good things for your child.
So, when the "...I can do it because I am grandpa strikes..." lead with concern and education. If it comes down to general concern and education not working. Remember you are the parent. You set the rules and limitations for your child. This can be sad and painful for both sides, but it is your job to set the boundaries as the parent. I personally feel strongly about issues that affect development of my children. I do not feel bad for setting boundaries if developmental process or safety is a concern and neither should you.