“The Early Life of Jefferson Davis “is a booklet I found at the First White House. It was written by Walter L. Fleming, published by the University Bulletin at Louisiana State University, June, 1917, and reprinted by Charles Estell Baker, D.D. in Birmingham, Alabama in 1993.  How I would love to get copies to sell at the First White House gift shop, as it is well written and well documented.
Fleming mentions several traditions in regard to the ancestors of Jefferson Davis, but the most satisfying one was put forth by William Whitsitt, in his book “Genealogy of Jefferson Davis and of Samuel Davies,” in 1910. Whitsitt traces the ancestors of the President back to “John Davis of Pencader Hundred in the County of New Castle upon Delaware Turner, and Anne Davis his wife.”
John Davis was thought to have been a Welsh immigrant, who signed his name with an x mark.  Evan Davis, his son, according to Whitsitt, was born in Philadelphia about 1702. Evan Davis went to the Welch Neck settlement on the Peedee river in South Carolina, and married a Mrs. Williams, whose maiden name was Emory. Their son, Samuel Emory Davis was the father of Jefferson Davis. Fleming writes “…we can be certain only of these facts: that Evan Davis was born in Philadelphia; that in middle age he went into the southwest to South Carolina and later to Georgia and that he left one son, Samuel Emory Davis, the father of Jefferson Davis.” 
Samuel Davis, Jefferson’s father, fought in the Revolutionary War, returned home and married Jane Cook. Jefferson was the youngest of their ten children. Jefferson said in his memoirs, about his mother: “She was of Scotch-Irish descent and was noted for her beauty and sprightliness of mind. My father…was unusually handsome and…a man of wonderful physical ability.”
Dr. Fleming writes that Samuel and Jane were earnest Bible students, who were members of the Baptist church and that they named all but one of their sons from names in the Bible. Jefferson was named for Thomas Jefferson. Fleming writes about the Davises: “they were good, sound Americans of the border, of the class that has given this country its best citizens and leaders.”