I have talked with some family members who object to using yDNA testing in Family History Research.  The concept of yDNA testing as a tool for genealogical research is based upon the theory that the y chromosome changes very little from father to son for several generations.  DNAProf. Sykes, a leading Oxford genetics authority believes that he can determine a man's paternal ancestry back into the ice age or 30,000 years ago.  The National Geographic Society's Genographic Study believes they have established the patterns of human migration through yDNA mapping of living human beings.  I have found other geneticists who disagree with the 30,000 year time frame and are turning the genetic (molecular) clock forward.  They hypothesize from analyzing yDNA and MtDNA samples from all over the world that all living humans may be descended from a common ancestor who lived as recently as  6,000 years ago!  It is not necessary that we accept every interpretation of Prof. Sykes or the National Geographic Society for us to find  yDNA tests helpful in establishing other living individuals with whom we share a common ancestor.

The Sorenson Molecular Foundation recently used yDNA testing to disprove  an anti-Mormon accusation that Joseph Smith  fathered children by other men's wives.  Such rumors were instrumental in the apostasy of some LDS in Nauvoo and even the martyrdom of the prophet.  There is now yDNA evidence that clears Joseph Smith.