In the book's own words, not ours, with obvious scanning errors fixed. Families often supplied these stories to the publisher, so check key dates.
Born 1806, Culpepper county
From History of Ray County, Mo. (1881)
ISAAC DUVAL.
Was a native of Virginia. He was born in Culpepper county, that state, July 16, 1806. Received the advantages of such schools as the times afforded, and was reared to be a farmer, and always pursued that calling. Isaac Duval was married in his native county, on the 6th day of November, 1837, to Miss Sarah M. Jeffreys. The issue of this marriage was three boys and one girl. He moved to Ray county, Missouri, in the year 1844, and settled in Richmond township. His wife died July 3, 1845, and he was was afterwards married to Mrs. Rebecca Mausur, relict of Charles Mausur, Senior. Mr. Duval removed about the year 1849, to Grape Grove township, and purchased the farm upon which he lived at the time of his death. He was inclined to Lutheranism in religious views, though he was not a member of any denomination. He was a member of the Millville Lodge of A. F. & A. M. Isaac Duval died, November 17, 1879, highly respected by all who knew him. A good man and valuable citizen is gone.
As printed in History of Ray County, Mo. (1881). See the original pages. Wording is the original; obvious scanning errors have been corrected, and a few may remain.
Their biographies name Isaac Duval: Hiram P. Settle
The printed record stops around 1881. We trace your line from there down to you, with every source cited.