The city of Vanhoover is the place "Where Everypony's Family". Pinkie Pita isn't sure if she believes that, but it seems true enough. After all, she enjoys her job and the place where she lives, and she can't imagine asking for much more out of life.
Today, though, she discovered something new about herself. And it doesn't make any sense at all.
[No overt spoilers for "Pinkie Apple Pie", but you won't get the story if you haven't seen the episode.]