Variation I: Genetics
This chapter reviews the main approaches for characterizing preference genetics. Approaches to understanding the genetics underlying preferences (or any other phenotype) take two broad forms. The first approach consists of attempts to identify particular genes or genomic regions associated with preference variation; for preferences, this is typically done using so-called forward genetics, whereby variation in phenotype is correlated with variation in genotype. Alternatively, the effects of candidate genes on preference can be characterized using reverse genetics, whereby gene structure or function is altered to test its effect on phenotype. The second approach encompasses quantitative genetic studies that assume that the underlying genetic variation is continuous and additive. Quantitative genetic models often assume an infinite number of loci each contributing infinitely small positive or negative effect, summing to determine trait value.