Should Parents Expect a Return on Their Investment in College?

Recently I was reading a New York Times column where a father of college freshman wrote in with the following dilemma:

My wife and I are spending a fortune to send our son to an Ivy League college. Over the holidays he came home and told us that he loves agricultural science class and wants to volunteer at a sustainable farm over the summer. Excuse me, but I am not paying $60,000 a year (after taxes) for him to be a farmer. My wife tells me to relax; his interests will probably change. He is...