ObjectiveWe investigated how different levels of prenatal exposure to testosterone influence physiological reactions to dyadic interactions, hypothesising that higher levels of prenatal testosterone are linked to greater physiological responses.MethodAutonomic nervous system responses to dyadic interactions focussed on social or physical norms were measured. Physiological assessment of excitability (heart rate, facial temperature) and a behavioural assessment (Likert items judgements) were run on 25 neurotypical participants who had distinct testosterone exposure levels in utero. In utero exposure to testosterone was assessed measuring 2D : 4D (ratio between the lengths of the index and the ring fingers).ResultsHigher testosterone exposure participants showed greater physiological arousal: a greater heart rate decrease, independent from scenario type (p<0.05), and opposite facial temperature changes in response to social (increase) (vs.) physical scenarios (decrease) were found (Left-cheek: p<0.05; Right-cheek: p<0.05).ConclusionThese findings suggest a long-term influence of prenatal environment on adults’ physiological responses during social situations.