Assortative Mating is a Natural Consequence of Heritable Mate Preferences and Preferred Traits

Assortative mating – the tendency to choose partners similar to oneself – is the most ubiquitous phenomenon in mate choice. Despite numerous proposed explanations, a parsimonious mechanism has been overlooked: when individuals choose mates based on heritable traits and preferences, offspring inherit a trait from one parent and the corresponding preference from the other, creating genetic correlations that link having a trait to preferring that same trait. To evaluate this non-adaptive mechanism, we developed an agent-based model simulating 100 generations where agents, with traits and preferences each uniquely determined by 40 loci, chose reproductive partners based on preferences. Genetic correlations formed between preferences and preferred traits within individuals, as well as between partner traits (i.e. assortative mating). While not contradicting existing explanations, our simplified model revealed that heritable variation in preferences and preferred traits is sufficient to drive a universal pattern of assortative mating in the absence of more complex dynamics.