“…Another direction for future research, despite that the digit ratio has been used extensively in the literature ( Fink et al, 2003 ; Voracek and Loibl, 2009 ; Manning J. et al, 2014 ; Manning J. T. et al, 2014 ), is to rely on more objective tools to capture hormonal exposure, such as physiological measures of circulating testosterone or baseline levels on such hormonal factors ( Nave et al, 2018 ; Dinsmore et al, 2021 ; Nepomuceno and Stenstrom, 2021 ). Although circulating testosterone in adults is not necessarily a reliable indicator of prenatal testosterone exposure, which is when sexual differentiation of the brain takes place ( Arnold, 2020 ; McCarthy, 2020 ), future research should examine whether the current results can be extended to more objective measures of hormonal exposure.…”