The Illumina GoldenGate assay was used for SNP genotyping (Jazwinski et al. 2010 (link)). SNPs were selected according to the Illumina Assay Design Tool, and quality control measures were applied using Illumina GenomeStudio. For SNP and sample clustering, the 10th percentile GenCall score was set at 0.4. Samples with call rates below 90% were excluded. UCP2/3 are located in tandem on chromosome 11, and the three SNPs analyzed in this study are polymorphic and in Hardy-Weinberg equilibrium (Table 1). To examine the additive genetic effect of each SNP in the multiple linear regression analysis, its genotype was numerically recoded according to the copy number of the minor allele (0, 1, 2).