I can be thankful for several items which have shown up in abundance during my family history research.
1 - My paternal grandmother's ancestors were mostly of the Society of Friends (Quakers), which explains why she was into genealogy (bequeathing her interest to yours truly) and why several of her ancestral lines have been traced way back -- with documentation!
2 - My many ancestors who fought in the War Between the States -- most of them on the Confederate side. Discovering while I was still a boy that I had a Johnny Reb in my tree taught me to be more open-minded about the Southern rebellion (and other issues) and to read critically what the textbooks say. From being a little boy who considered slavery the only cause of the War and the Rebels to be evil I have matured into a middle-age member of Sons of Confederate Veterans.
3 - I've discovered that many of my ancestors served in our country's military (only a couple made military service their career). This didn't surprise me, because both my parents and most of their siblings served in either the Army or the Air Force. But in addition I've uncovered that several of my forebears on both sides were clergy (all of them either Methodist or Baptist). I suppose that thanks to these two facts it was in my genes (I was destined) to combine the two professions. You see, I served as an Army chaplain of the Disciples of Christ, at posts in Texas and Tennessee in the 1980s.