Do sex hormones at birth predict later-life economic preferences? Evidence from a pregnancy birth cohort study

Abstract

Economic preferences may be shaped by exposure to sex hormones around birth. Prior studies of economic preferences and numerous other phenotypic characteristics use digit ratios (2D : 4D), a purported proxy for prenatal testosterone exposure, whose validity has recently been questioned. We use direct measures of neonatal sex hormones (testosterone and oestrogen), measured from umbilical cord blood ( n = 200) to investigate their association with later-life economic preferences (risk preferences, competitiveness, time preferences and social preferences) in an Australian cohort (Raine Study Gen2). We find no significant associations between testosterone at birth and preferences, except for competitiveness, where the effect runs opposite to the expected direction. Point estimates are between 0.05–0.09 percentage points (pp) and 0.003–0.14 s.d. We similarly find no significant associations between 2D : 4D and preferences ( n = 533, point estimates 0.003–0.02 pp and 0.001–0.06 s.d.). Our sample size allows detecting effects larger than 0.11 pp or 0.22 s.d. for testosterone at birth, and 0.07 pp or 0.14 s.d. for 2D : 4D ( α = 0.05 and power = 0.90). Equivalence tests show that most effects are unlikely to be larger than these bounds. Our results suggest a reinterpretation of prior findings relating 2D : 4D to economic preferences, and highlight the importance of future large-sample studies that permit detection of small effects.

Digit ratio (2D:4D) and maternal testosterone-to-estradiol ratio measured in early pregnancy

“…In addition to hormones measured from amniotic fluid and maternal circulation, some researchers have examined concentrations present in umbilical cord blood assayed at birth. Taken together, the findings of these studies indicate no association with 2D:4D 48 , 50 – 55 . This is consistent with hormones sampled in this way representing late gestation 56 , whereas sexual dimorphism in 2D:4D has been detected much earlier 57 , 58 .…”

Born to Be Wild: Second-to-Fourth Digit Length Ratio and Risk Preferences

“…Thus, they could replicate some of the earlier findings, but could not replicate the findings of Stenstrom et al (2011) and Bönte et al (2016) who find a significant negative association between the digit ratio and the response to a question about the general preference for risk taking, albeit for the right hand only and not for women separately. Further, Van Leeuwen et al (2020) and Neyse et al (2021), who used the largest sample to date (3431 respondents), found no significant association between the digit ratio and general risk preferences. Gaining insights into the digit ratio's association with a general risk preference measure is of particular interest because recent studies have argued that compared to, e.g., lab-experimental measures of financial risk taking, a general risk preference measure has a higher validity for real-world risky choices (Charness et al, 2019;Kapteyn and Teppa, 2011;Verschoor et al, 2016).…”

“…This association is assumed to follow from (prenatal) testosterone's positive association with the preference for risk taking (Coates et al, 2010;Cronqvist et al, 2015;Nofsinger et al, 2018) and the digit ratio's status as a retrospective biomarker of prenatal testosterone exposure; higher exposure is thought to decrease the digit ratio (Manning et al, 1998;Manning et al, 2003;Manning, 2011;Voracek, 2014). 1 These assumed relationships have been questioned (Hönekopp et al, 2007;Voracek, 2014;Van Leeuwen et al, 2020;Warrington et al, 2018) and empirical evidence of the digit ratio's association with risk preferences has thus far proved inconclusive (Neyse et al, 2020).…”

“…The lack of replicability of the association between the digit ratio and risk preferences could be due to the absence of a relationship between the digit ratio and the preference for risk taking (Neyse et al, 2021), small sample sizes in combination with a small effect size (Apicella et al, 2015;Dupont and Plummer 1998;Van Leeuwen et al, 2020), or measurement error in the elicited digit ratio (Ribeiro et al, 2016). To date, sample sizes in the literature have ranged from around 50-700 observations (Neyse et al, 2020), except in Neyse et al (2021) who used a sample of 3431 respondents.…”

Masculinity and Lying

“…Several studies have cast doubts on the validity of 2D:4D as a proxy for prenatal testosterone exposure. These studies find no correlation between 2D:4D and testosterone levels in umbilical blood or mother's blood (Hickey et al, 2010;van Leeuwen et al, 2020). However, these methods to measure foetal hormonal levels are imprecise.…”