I don't know the answer to your question, but I am also looking for it. I believe my ancestor was their sister, Elizabeth. My mere speculation is that they are the children of John Brown and Ann (Nancy) Emmons. They were born in approximately 1777 and 1785 respectively. They were also in Madison County around 1840, but by 1850 they had removed to Hancock County, IL where they died and are buried. Again, at this point this speculation. I feel strongl that all of these Madison County Browns are connected, but I'm not 100% sure. Given the dates, this is how it all best fits together. Let me know if you've found anything on the question.