We've developed the app to help everyone measure their relative testosterone/estrogen levels based on the previous research in the field of development biology. The primary point of the app is to help you with understanding what the ratio of your fingers could mean for you. There are several papers that talk about how ratio of index and ring fingers point to levels of testosterone and estrogen in prenatal bodies. Males and females generally have different finger proportions. In males, digit 2 (index finger) is shorter than digit 4 (ring finger), but in females digit 2 is the same length or longer than digit 4. The second- to fourth-digit (2D:4D) ratio correlates with numerous behavioral and physiological conditions. *** The app is designed for entertainment purposes only.