Quality assessment of the data was carried out using PEDSTATS [60], and in-house SAS (SAS Institute, Cary, North Carolina, United States) and R (The R Project for Statistical Computing [http://www.r-project.org]) scripts. These tools allowed us to check that pedigrees were self-consistent, and to identify univariate and multivariate outliers. Outliers and other unusual trait values were inspected against the original records whenever possible.
