As to relatives, my paternal grandmother moved from Arkansas to California in the '30s and it seems we have a member from her line who was a General for the Union even though he was from Arkansas. Most people don't know that every Confederate state sent at least a regiment to fight for the Union. My paternal grandfather's parents immigrated to the USA from Finland in 1918 and thus have no connection to the Civil War. I am not sure of connections on my mother's side.
We had numerous relatives on both sides of the family, who fought on both sides of the war. One enlisted as a private in one of the Confederate armies (can't remember which) and eventually rose to the rank of either lieutenant or captain (once again, can't remember).
The two most prominent were Edwin Campbell and Jack Biggs.
Edwin Campbell was an officer in the 23rd Ohio Infantry under Rutherford B. Hayes in the early stages of the war, and was wounded at the Battle of South Mountain the day before Antietam. After convalescing back home, he helped form the 10th Ohio Cavalry under Charles Smith, and served in the regiment as a captain. Dear Lizzie, by Willian H. Jacobs, (one of my uncles/great uncles) is a series of books collecting letters written by Campbell to his wife (Elizabeth's were lost) during the War. It's a five-volume series and I think they're all available on Amazon.
Jack Biggs was an enlisted man in the 5th Missouri Cavalry, and was part of Union forces who helped chase Sterling Price back out of Missouri during Price's Raid in 1864.