AMID THE STAID and stately stone and brick homes along the north side of St. Louis’s Forest Park sits one house that’s impossible to miss. As a child, the 48-year-old artist Katherine Bernhardt, who grew up a couple of miles away in Clayton, would marvel at the boxy, three-story structure — a commingling of mostly rectangular forms and cutouts, with a white plaster surface and a frame that stretches past the living quarters — through the window of her parents’ minivan as they drove past it. Four years ago, she and her now-12-year-old son, Khalifa, moved back to her hometown from New York, where she’d spent more than two decades, in part to be closer to her parents but also because she was seeking a change. On a whim, Bernhardt went online to see if the property was for sale; she was handed the keys six months later.