Are We Over Informed?

The brunette twin's blood test came back with high cholesterol numbers. This is not surprising given that high cholesterol and high blood pressure run on Daddy's side of the family. The doctor told me she needed to watch what she ate, reduce her fast food consumption, avoid dairy, limit high cholesterol foods, eat veggies and fruits.
It's not that I'm taking her diagnosis lightly, but I cannot wonder if we are over informed about some things. I realize it's good to know that you have high cholesterol because it can cause heart problems later in life, but the brunette twin is nine years old. Isn't that a bit young to start monitoring her diet and spending all our time telling her she can't eat this or that because she has high cholesterol?
The irony is that we eat pretty much what the doctor suggested. I don't remember the last time we drove through a fast food restaurant to get dinner. I'm actually not sure that has ever happened in our family. They eat a nearly vegetarian diet. There are the occasionally hot dogs, hamburgers and bacon. Neither girl eats much meat, though. They do eat a lot of cheese and drink a lot of milk, so I guess we're going lower-fat and reducing those items.
The girls have gym at school every day. We walk to and from school every day. I know they get their exercise. At home the brunette twin wants nothing more than to sit and read as much as possible. I'm certainly not going to stop her from reading so she can exercise more to reduce her cholesterol.
Information is a difficult thing sometimes. I realize we need to take her high cholesterol seriously and we will. I'm sure there are additional dietary changes we can (and will) make. I'm just not sure we have enough information to understand why she has high cholesterol to really understand the steps we need to take.