What causes stress?

I'm sitting here at my desk, working away, thinking about something I saw on J's dresser. About an hour ago I decided to check his online grades and saw that he got an F on an assignment for his Health class. I had gone upstairs afterwards to see if I could find the assignment in his room. I looked on top of his dresser because there were papers piled on it and if an assignment was anywhere in his room, it would be on top of his dresser.

There was a green folder on top of the dresser, and this I knew was his Health folder. I decided to take a peek and look for the assignment. That kid has no sense of organization - I found a History assignment! I also found a different Health assignment covering the topic of Stress. Glancing through, I learned that my husband and I are #3 on J's list of stress causers (is that a word??). Now, how can parents cause stress? Really. Think about it. We want our children to do their best in school. We try to teach responsibility by doling out chores to the kids. Is it our fault that our child chooses not to do his best in anything? Is it our fault he is getting bad grades? I don't think so. I think it's his problem because he has decided to just skate by and do the least amount of work. Is it our fault that we want him to learn what it means to be accountable for his actions? I don't think so. How are parents causing stress on their kids? Maybe someone needs to enlighten me.