Parental Income and the Sexual Behavior of Their Adult Children: A Trivers–Willard Perspective

Abstract

Parental income is negatively and linearly related to the digit ratio (2D:4D; a proxy for prenatal sex steroids) of their children. Children of parents with high income are thought to be exposed to higher prenatal testosterone and develop lower 2D:4D. It is further hypothesized that 2D:4D relates to sexual orientation, although it is unclear whether the association is linear or curvilinear. Here, we consider patterns of parental income and its association with the sexual behavior of their adult children in a large online study (the BBC internet study). There were curvilinear relationships with parental income in male and female children. The highest frequencies of homosexuality and bisexuality were found in the lowest income group (bottom 25% of the population), the lowest frequencies in the income group representing the upper 50% of the population, and intermediate values in the other groups (low 50% and top 25% of the population). Parental income showed a U-shaped association with scores for same-sex attraction and an inverted U-shaped association with opposite-sex attraction. Thus, for the first time, we show that same-sex attraction is related to parental income. The curvilinear relationship between parental income and sexual behavior in their adult children may result from an association between very high fetal estrogen or testosterone and attraction to partners of the same sex. Among non-heterosexuals, and in both sexes, very high fetal estrogen may be associated with femme or submissive sexual roles, and very high fetal testosterone with butch and assertive sexual roles.

Digit Ratio (2D:4D; Right-Left 2D:4D) and Multiple Phenotypes for Same-Sex Attraction: The BBC Internet Study Revisited

“…The negative association between 2D:4D and family income led to a study concerning parental income and same-sex attraction. Curvilinear relationships were found such that, in comparison to children from average-income parents, the children from low-income and high-income households reported elevated rates of same-sex attraction in both sexes (Manning et al, 2022a ). These U-shaped relationships provide further support for a relationship between low and high testosterone or high estrogen and male androphilia and female gynephilia.…”

“…We consider a model that represents a modified version of the Trivers-Willard hypothesis (Manning et al, 2022a , 2022b ; Trivers & Willard, 1973 ). The model assumes that (1) the variance in direct fitness for males is greater than that for females (see Bateman, 1948 ), (2) variation in maternal condition (e.g., in response to resource availability; Mathews et al, 2008 or maternal stress; Ward & Weisz, 1980 ) affects fetal sex steroids, (3) this leads to fitness consequences in the offspring.…”

“…Digit lengths were self-reported. As in previous reports of the BBC study (Manning et al, 2007 , 2022a , 2022b , 2023 ), we restricted our analyses to participants with 2D:4D in the right and left hands within the range of 0.80–1.20. We did this because finger lengths that are self-measured occasionally include measurement errors that result in extreme values of 2D:4D outside the range of 0.80–1.20 (e.g., Manning et al, 2007 ).…”

Parental Identity and Lived Experiences when Parenting a LGBTQIA+2 Child: A Critical Narrative Synthesis of Current Evidence

“…The concept of identity has been studied in the context of the LGBTQIA + 2 population in terms of their innate identity, their identity in society, identity expression, etc. (Manning et al, 2022 ; Stotzer, 2011 ; Vázquez et al, 2023 ). This review shifts the identity lens more closely to focus on the perspectives of parents to explore their identity change in the context of their child’s disclosure and its implications.…”