Take a look at your right-hand. Which of your fingers is longer: your ring finger, or your index finger?
John Manning's book "Digit Ratio: A Pointer to Fertility, Behavior and Health" reviews evidence to suggest that the ratio of the length between the ring and index finger is determined during early fetal development, and is influenced by sex hormones, particularly testosterone. If this is true, the fingers may provide a permanent, and easily visible, historic marker of important hormonal events that occurred during a critical time of fetal development, the latter part of the first trimester. This is a critical time of sexual differentiation of both the brain and body.
Generally, males have a ring finger that is longer than their index finger. Females typically have index and ring fingers of about the same length. The ratio of index finger to ring finger length is called the “2D:4D digit ratio". Males generally have a digit ratio below 1.00 -- they have what is termed a "low digit ratio." Women generally have a digit ratio of about 1.00
http://human-nature.com/nibbs/02/manning.html
I'm interested in what digit ratios we girls (and boys) have. To start things off, my ratio is 0.99, my ring finger is ever so slightly longer than my index finger.
Remember, it is index finger length divided by ring finger length. Measure from the first crease to the finger tip.