Variation in Human Mate Choice: Simultaneously Investigating Heritability, Parental Influence, Sexual Imprinting, and Assortative Mating By: Phillip Skaliy

Terms Assortative Mating – the frequency at which individuals mate with persons of similar phenotype (positive assortative mating) or different phenotype (negative assortative mating) Sexual Imprinting - individuals acquire mate-choice criteria during development by using their opposite-sex parent as the template of a desirable mate MZ – monozygotic (identical twins) DZ – dizygotic (non-identical twins)

Overview Human mate choice is essential to evolution Basis of variation in mate choice is not well understood Look at twins, partners, parents Test for genetic and family environmental influences on mate choice Different traits analyzed Test for sexual imprinting

Background Studies before this Romantic partners correlate positively on age, social attitudes, and religiosity Believed that similarity between partners is due to initial choice (assortative mating) Conflicting results – why do we choose a particular mate over another Constraints of mating market Could be genetic or non-genetic

Background Possible non-genetic/environmental factor is the influence of Parents on mate decision Ensure daughters marry successful men Sexual Imprinting Opposite sex parent as template for mate Traits looked at: Education, yearly income, Religiosity, Social attitudes, Personality, Height and age, Body mass index (BMI), Length of relationship

Experiment Non-genetic it should be revealed in a twin study as a family environmental effect on females for mate choice regarding investment-related traits. Genetic influences See if there is any similarity or correlations between the twin’s spouses and see if there is a difference between the spouses of MZ and DZ twins Sexual Imprinting Twin’s partner should be more similar to the twin’s opposite- sex parent than to a co-twin or a same-sex parent

Table One 22,861 individuals from 6,105 independent families

Table 2 In this table it is clear that twins’ partners were not more similar in any trait to the twins’ opposite-sex parent than to the twins’ same-sex parent. That’s a strike against the imprinting thesis.

Table 3 Table 3 shows that partners correlated very weakly on some traits (e.g., income and personality) but strongly on others (e.g., religiosity and attitudes). Table 3 shows that partners correlated very weakly on some traits (e.g., income and personality) but strongly on others (e.g., religiosity and attitudes).

Table 4 - shows the correlations between twin pair partners on each trait Notice that there’s not a difference between MZ and DZ females for income.

From the tables Twin’s Partners correlated weakly on most traits but positive on some Correlation between twin pair partners was not significant for BMI, height, and all personality scales, but there were small but significant correlations between twin pair partners for education, income, religiosity, attitudes, and age. Tested to see if there was a difference between MZ and DZ partners, but there was none (correlation not higher in MZ) indicates no significant genetic influence on mate choice

From the tables Specifically for income and age, correlations between female MZ and DZ twin pair partners were highly significant and similar in size, indicating a genuine family environmental influence on women’s mate choice for these traits even after controlling for assortative mating There was no evidence for the sexual imprinting hypothesis. A twin's spouse was much more similar to the twin and co-twin than the twin's opposite-sex parent. For the heritability of each trait, twin pair correlations were significantly greater for MZ pairs than for DZ pairs

Discussion Overall, found that genetic variation accounts for very little individual variation in human mate choice. Twin’s partners correlated very little Furthermore, there were no significant genetic effects on mate choice in either males or females for any individual trait. it is remarkable that a choice behavior so central to individuals’ lives exhibits a near-zero genetic component But choice of mate requires reciprocity

Discussion One positive finding in the results is an influence of family environment on female mate choice in terms of the income and age of a partner parental influence is expected to primarily involve pressure on a daughter to mate with successful man There was little evidence for substantial familial effects on other aspects of mate choice. Main conclusion: Despite being one of the most important choices in human life, variation in partner choice followed no apparent order aside from a small family environmental influence on the age and income of females’ mate choices and the similarity of partners in some traits.

Improve Study Study different traits – pheromones, facial characteristics Look at newlyweds and see if there is a difference Done in Australia – different environmental influences

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