<![CDATA[The 2D:4D ratio (index to ring finger length) is a non-invasive biomarker of prenatal sex hormone exposure, consistently reported to be lower in males than in females. However, data on this ratio among Indonesian adolescents remain limited. This study analyzed the correlation between the 2D:4D ratio and sex among junior high school students at SMP Methodist Antiokhia Pancurbatu. An observational analytic cross-sectional study used total sampling of 394 respondents (198 males, 196 females). Finger lengths were measured with a millimeter ruler, and the ratio was calculated by dividing 2D length by 4D length. Data were tested for normality with the Kolmogorov-Smirnov test and compared between sexes using the Mann-Whitney U test. Mean index and ring finger lengths were 6.56 ± 0.55 cm and 6.46 ± 0.63 cm, with an overall mean 2D:4D ratio of 1.02 ± 0.10. Absolute finger lengths differed significantly between sexes for both the index finger (U = 12539.00; Z = −6.119; p < 0.001) and ring finger (U = 12978.00; Z = −5.714; p < 0.001), with males having longer fingers. However, the 2D:4D ratio did not differ significantly between males (1.018 ± 0.096) and females (1.025 ± 0.099) (U = 18560.00; Z = −0.749; p = 0.454). These findings suggest that absolute finger dimensions reflect clear postnatal sexual dimorphism, whereas the 2D:4D ratio shows only a very small, statistically undetectable difference in this population, likely influenced by measurement precision and sample characteristics.]]>
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