Ugo Perego et al., reports on how DNA study rules out 2 possible Smith descendants; casts strong doubt on third.
Ugo A. Perego, Natalie M. Myres and Scott R. Woodward, "Reconstructing the Y-Chromosome of Joseph Smith: Genealogical Applications," Journal of Mormon History 31, no. 2 (2005): 42-60
When we compared the Y-chromosome obtained from a male descendant of Orrison Smith to the Joseph Smith haplotype, we found nine differences between the two. (See Table 5.) Thus, this finding provides strong supportive—but not conclusive—evidence that Orrison Smith was not Joseph Smith's son.
However, since only one descendant of Orrison Smith contributed a DNA sample, we could not infer Orrison's Y-chromosome haplotype. It requires at least two direct male descendants to recon struct the Y-chromosome haplotype of their most recent common paternal ancestor. A non-paternal event, such as adoption or illegitimacy, in the four generations that separate Orrison Smith from the individual tested could be responsible for the different Y-chromo some haplotype. For this reason, Orrison's Y-chromosome cannot be confidently inferred. To exclude the possibility of a non-paternity event, further DNA sampling from descendants sharing a documented genealogy with Orrison Smith's paternal line is needed.
As displayed in Table 5, the highly significant differences existing among the haplotypes of the three case studies (Moroni Pratt, Zebulon Jacobs, and Orrison Smith), when compared to the Joseph Smith inferred haplotype, identify each one as representing a separate and distinct paternal lineage. Collectively, this study provides each family with additional reliable information for evaluating suspected genealogical relationships.