As a native Briton, I've always been puzzled by this statement. I grew up eating home-baked apple pies, and enjoyed it as part of our traditional English cooking. Not only is Britain an assemblage of countries much given to pie-making, but England in particular is famous for its apple varieties, and the county of Kent for its apple orchards. So, nice though it is that Americans appreciate a good apple pie (and grow plenty of apples themselves), it still seemed odd that they would claim such a basic dish as distinctly their own. And Google today, in its recipe-per-state Independence Day feature, acknowledges the apple pie's true homeland, in the Maine tab.
HAPPY FOURTH OF JULY!