More kinship (Focus on kin-recognition cues)  Further implications of kinship. - The “Cinderella effect.” - Incest avoidance and sexual disgust. - Nepotistic nosiness. Evolved psychology of kin recognition. Lens model of kin recognition. Kin recognition cues. Trickability and overgeneralization. (Implications for perceiving non-kin as “kin”)

Some contexts in which it would have been adaptive to respond to people differently depending on genetic relatedness… [Help close kin] [Avoid mating with close kin] [Avoid hurting close kin] [Encourage close kin to mate “wisely”]

Results from analyses of 1974-1990 homicide data in Canada The “Cinderella effect”: Risk of being injured or killed by step-parent is higher than risk of being injured or killed by biological parent. Results from analyses of 1974-1990 homicide data in Canada (Daly & Wilson, 1996)

Incest avoidance and sexual disgust: Mating relationships with close kin pose problems for offspring fitness. Mating relationships with close kin are extremely rare. Thinking about mating with close kin arouses disgust. (Especially among women.)

Nepotistic nosiness: People meddle in the mating relationships of their kin. People meddle especially in the relationships of close kin. (Especially close female kin.) Example: Vigilance. (Faulkner & Schaller, 2007)

Nepotistic nosiness: People meddle in the mating relationships of their kin. People meddle especially in the relationships of close kin. (Especially close female kin.) Example: Vigilance. (Faulkner & Schaller, 2007) Example: Daughter-guarding. (Perilloux, Fleischman, & Buss, 2008) Parents attempt to control daughters’ sexual behaviors and mate choices more than they attempt to control sons’ sexual behavior and mate choices.

Genetic relatedness matters! But: How do our minds assess genetic relatedness? (Evolved psychology of kin recognition)

Lens model of kin recognition: Cues: “Maternal perinatal association” Co-residence Phenotypic Similarity Emotional closeness Emotional, cognitive, and behavioral responses that were adaptive in the context of kin (more trusting; more prosocial; less sexual; etc.) Actual genetic relatedness Subjective “kinship” Potentially Trickable! Overgeneralization

Overgeneralization of co-residence as a kinship cue: “Westermarck effect” Childhood co-residence Sexual aversion Co-residence and moral attitudes about incest: Duration of co-residence with opposite-sex siblings Attitude that sibling incest is morally wrong (This effect occurs regardless of whether “siblings” are full-siblings, half siblings, or adoptive siblings.) (Lieberman, Tooby & Cosmides, 2003)

Overgeneralization of phenotypic similarity as a kinship cue: Effects of facial similarity on trust and attraction. (DeBruine, 2005) More trustworthy Less “lustworthy”

Overgeneralization of phenotypic similarity as a kinship cue: Effects of facial similarity on trust and attraction. (DeBruine, 2005) Effects of facial similarity on helpful and cooperative behavior. (Krupp, DeBruine, & Barclay, 2008) Effects of facial similarity on voter preferences in political elections. (Bailenson et al., 2009) Effects of other forms of similarity: - Similar attitudes implicitly connote “kinship.” - Similar names elicit more helping behavior.

Overgeneralization of emotional closeness as a kinship cue: Emotional closeness is typical of friendship. Is friendship akin to kinship, psychologically? Yes, somewhat, for women. (Not so much for men). (Ackerman et al., 2007)