Thanks to Ancestry.com, DNAngels, and matches from distant cousins, definitive answers came while I was in St. Louis. Going with the flow, we spent a day with Ilene (82), my paternal grandmother, who lives in St. Charles. We visited Steve (61), my biological father, who lives in a nursing facility in Jennings.
The kids and Ilene enjoyed City Museum, which is truly "weirdly wonderful" with its slides, tunnels, caves, collections, and sculptures.