DNA testing has been employed to study the ancestry and posterity of Joseph Smith Jr., founder of the Mormon movement. Thanks to information found on the paternally inherited Y chromosome, for example, researchers have been able to establish a likely Irish origin for the Smith line. Y chromosome testing has also been helpful in resolving a number of paternity cases involving men who were allegedly sons of Joseph through polygamous unions. To date, all of the tests for these candidates have borne negative results.

However, the strongest case for a child born through one of Joseph Smith’s plural marriages is that of Josephine Lyon, born on February 8, 1844, in Nauvoo, Illinois. Because Josephine did not receive the Y chromosome from her biological father, her paternity could not be verified through science until recently. Josephine’s mother, Sylvia Sessions, was sealed to Joseph Smith even though she was legally married to (but likely separated from) Windsor P. Lyon. Details about Sylvia Sessions’s unions to both men—particularly to Smith—are highly debated among historians. This is probably due to the affidavit Josephine Lyon signed in 1915, in which she stated:

Just prior to my mother’s death in 1882 she called me to her bedside and told me that her days on earth were about numbered and before she passed away from mortality she desired to tell me something which she had kept as an entire secret from me and from others but which she now desired to communicate to me. She then told me that I was the daughter of the Prophet Joseph Smith, she having been sealed to the Prophet at the time that her husband Mr. Lyon had was out of fellowship with the Church.

The purpose of this report is to summarize the steps that were taken to establish the biological paternity of Josephine Lyon through the analy­sis of autosomal DNA from descendants of both Joseph Smith and Josephine Lyon.