in the Wilhelm et al. study was an F2 derived from 2 inbred strains (C57Bl/6J and DBA2/J), compared to the 8 inbred strain cross that was used to derive the HS/Ibg. Overall, any genetic correlation (or lack thereof) is specific to the population in which it is observed, although greater genetic diversity may allow a greater ability to generalize from a particular population to the species in general (Falconer and Mackay, 1996).
