Start looking for you grandfather and his siblings on the internet for Ellis Island Immigration Records. St Louis is in Missouri not Illinois. Look at the 1930 US Census records just released to see if you can find him there. Also consider asking the court that handled your adoption for the information that you seek, some courts are starting to open records so that children can locate their birth parents, especially if there are medical problems. Also consider going to The Family History Library, part of, but not at all locations of The Church of Jesus Christ of Latter-day-Saints (The Mormons). The volunteers at the library will take you by the hand and guide and direct you in your research. They will not do it for you. The only cost to you will be for photo copies, about $.05 each and $4.00 for postage to cover cost of getting and returning microfilms from the main library in Salt Lake City, UT. The church has information in their archives from all around the world. Good hunting for information on your roots.