Researching the Mclain Family

researching the McLain Family. Have hit a "road block" in researching this family with my 3rd great grandfather, William McLain. He married Mary Aloysia Layton in Nelson Kentucky in 1807. Later moved to Perryville, Missouri before 1820. I have a great deal of information on the family from the time they moved to Missouri. I have no information on William McLain before he married Mary Aloysia Layton. I would welcome any information on this William McLain and his family.