Chromosomes yielding LOD scores > 1.0 in both parametric and VC sex- and age-adjusted analyses were followed up with multi-point oligogenic joint linkage and segregation analyses using Bayesian MCMC methods implemented in LOKI 2.2 [8] with sex and age as covariates. The effect of non-normality has not been reported in the context of LOKI's MCMC approach; therefore, the trait values for non-smokers were treated as unknown so that the data were less skewed. The initial estimates (the "priors") for the number of QTLs and the tau beta (i.e., variance in the genotypic effects) were set at 2 and 20, respectively, based on oligogenic segregation analyses, and a limit on the residual variance was set at 75 to improve mixing (i.e., allowing the sampler to visit various parts of the sample space for the parameter estimates). We defined a "large QTL" as a locus with an individual contribution of at least 5% of the total variance of the trait. Since the Bayesian analysis method used does not provide traditional LOD scores or p-values, the results were used to provide a count
