Why kids from lower-income families retain less over the summer than kids from higher-income families

According to the lady on the radio, its because they don't have access to museums and other cultural places to stimulate their brain over the summer. I have almost rolled my eyes out of my head. People have to have excuses for every thing (me included). But that is NOT the reason kids don't retain stuff over the summer. Ever heard of a library? They're free. My kids have learned so much from me just reading to them. Since we homeschool, I plan on taking a break in the summer, but we are still going to do school at least a few days a week, even if its only a review math sheet every day or so. I'm not sure what the exact statistics are, but I heard that teachers spend like the first 6 weeks of the school year reteaching material the kids have forgotten over the summer. Yet another reason to homeschool. :-)