Selective neutrality predicts that the distribution of the additive genetic variance explained as a function of MAF is uniform (Eyre-Walker 2010; Visscher et al. 2011). For example, loci with MAF between 0 and 0.01 should account for 2% of the additive genetic variation, and loci with MAF between 0.01 and 0.50 should account for the other 98%. Furthermore, the proportion of genetic variation that is non-additive should be lower in neutral traits than in traits under directional or stabilising selection because these forms of selection erode additive genetic variation (Fisher 1930; Merila and Sheldon 1999; Stirling et al. 2002; Penke et al. 2007). There should also be no systematic tendency for recessive alleles to influence a personality trait in any particular direction if it is selectively neutral (Lynch and Walsh 1998; DeRose and Roff 1999). Inbreeding depression, which only occurs in the presence of directional recessiveness (Lynch and Walsh 1998), is therefore not expected to affect personality traits if they have been selectively neutral.
