I am trying to find out the parents of my 4th great grandfather Isaac Alexander. Gedmatch connects me the various descentants of James Robert Alexander and a Family TreeDNA match connects me to a descent of John Rankin Alexander Sr. at 3rd/5th cousin. Isaac could be James Rankin's son but but the time between marraige and birth of Silas is very thight. Isaacs born about 1789 in NC and died in May 1855 in DeKalb, Tennessee. Any have any ideas?