Situational factors may have been an influence in determining which side someone would choose.I base this on something John R. Phillips said in his autobiography, "My Life Story."He wrote that his wealthiest neighbor in Marion County, Alex Underwood, was originally pro-Union. Then fearing he would lose everything, Underwood sided with the Confederacy.I believe John wrote the same thing about Oran Davis in Winston County.It should be noted that both of these men were the owners of many slaves.
In my research I found many instances of pro-Union slave holders--e.g. Green Haley and Burrell Howell, both of Marion County.Today, some people would have us believe the issue of slavery was the determining factor in whether someone would be be for the Union of Confederacy.I have seen quite a bit that undermines that position.