Although retroviral insertion can be used as a clue to relatedness they can give misleading results, so other methods need to be used to conclusively confirm relationships.
"Extensive data on genetic divergence among 24 inbred strains of mice provide an opportunity to examine the concordance of gene trees and species trees, especially whether structured subsamples of loci give congruent estimates of phylogenetic relationships. Phylogenetic analyses of 144 separate loci reproduce almost exactly the known genealogical relationships among these 24 strains. Partitioning these loci into structured subsets representing loci coding for proteins, the immune system and endogenous viruses give incongruent phylogenetic results. The gene tree based on protein loci provides an accurate picture of the genealogical relationships among strains; however,
gene trees based upon immune and viral data show significant deviations from known genealogical affinities "
W. R. Atchley and W. M. Fitch. Gene trees and the origins of inbred strains of mice. Science 254 (5031):554-558, 1991.