In principle, the approach of the previous chapter could be extended to many loci and many different possible alleles. For example, we might want to extend the sexual conflict example to predict what happens if there are different alleles that improve mating success to a different extent, and also cause reproductive failure of variable magnitudes in females. All we need to do is to keep track of an increasing number of possible mating pairs: for example, 10 different alleles means 10 × 10 = 100 different combinations of males and females. Hmm…can be done, but is hardly tempting. Still, this complication addresses one aspect of the problem only, i.e. how allelic variation should be dealt with. It gets worse, once we consider that many phenotypic traits are influenced by a multitude of loci, plus environmental variation. Population genetic models could, in principle, be built to find out rules of inheritance and the subsequent direction of evolution in such complicated settings, but this can get very tedious. Additionally, in most cases we also operate quite blindly: even in an era where we have the genome of humans, yeast, fruit flies and whatnot sequenced, we have typically no clue how many loci are involved in determining a particular trait, let alone being able to specify the effect of each allele at every locus.