Evidence is growing that this 'digit ratio' effect is real. Recently, strong evidence has emerged that men whose index fingers are longer than their ring fingers are significantly less likely to develop prostate cancer.
To work out the ratio of your fingers, measure the distance from the midpoint of the lowest crease at the base of the finger to the very tip -- the fingernail does not count.
A long index finger correlates strongly with a lower risk of early heart disease and, in women, a higher risk of breast cancer and greater fertility. People with relatively long index fingers are also more likely to suffer from schizophrenia, allergies, eczema and hay fever.
The Daily Mail reports:
"... [A] short index finger relative to the ring finger ... correlates with higher male fertility and sperm counts, higher levels of aggression and increased aptitude for both sport and music ... [D]igit ratio ... [correlates to] more than 100 psychological traits and propensities to various illnesses."
The length of your index finger relative to your ring finger may reveal some interesting clues about your health and personality.
Your 2D:4D digit ratio refers to the ratio of the length of your index finger (digit 2) and ring finger (digit 4). According to Digit Ratio: A Pointer to Fertility, Behavior, and Health by developmental biologist Dr. John Manning, who has been studying this issue for more than two decades, generally a man's index finger is about 96 percent the length of his ring finger, giving a "low" ratio of .96.
Women generally have a "high" digit ratio of 1.00, as their index fingers and ring fingers tend to be nearly the same length.
So far, the research shows that your digit ratio may give you clues to more than 100 psychological traits and illness risks.
What Does Your Digit Ratio Reveal?
To measure your digit ratio, measure from the lowest crease at the base of your index and ring fingers to the fleshy tip (when looking at your palm).
A low ratio (shorter index finger) signals greater fertility and aggression in men, along with an increased propensity toward sports or playing a musical instrument. Women with a low ratio are also more likely to be aggressive.
What's behind these apparent links?
Research by Manning and others suggests that greater exposure to testosterone in the womb increases the chances of having a more "masculine" hand, i.e. one with a shorter index finger. This testosterone exposure is also thought to be responsible for the range of traits associated with a low 2D:4D ratio, such as greater aggression and risk-taking behavior.
Higher estrogen exposure in the womb, meanwhile, may lead to a longer index finger, or high 2D:4D ratio, and estrogen exposure is also linked to breast cancer and heart disease risk.
Remember -- You Have the Ultimate Control Over Your Genetic Destiny
There is some compelling research showing that exposure to less than ideal hormone concentrations during critical developmental stages may alter not only the length of your fingers but also your personality and risk of developing certain diseases.
But there is a danger in resigning yourself to the fact that you are going to die early or act a certain way as a result of your genes predetermining your health. In reality, nothing could be further from the truth, as you have ultimate control over your genetic expression.
The new field of epigenetics has shown that the choice of which of your genes are "expressed," or activated, is strongly affected by environmental influences.
It is actually the cell's membrane -- operating in response to environmental signals picked up by the membrane's receptors -- that control the "reading" of the genes inside. And your actions, lifestyle and even your thoughts make up these "environmental signals."
In other words, no matter what hand (or finger length) you were dealt at birth, you can take steps to "activate" the disease-busting, health-boosting genes and suppress those that will cause you harm. This is evidenced perhaps most clearly by identical twins, who start out with the exact same genetic code … but end up very different.
Epigenetic "malleability" helps to explain why identical twins become distinct as they age. As you age, your genome does not change but your epigenome changes dramatically, especially during critical periods of life, such as adolescence. It is influenced by physical and emotional stresses -- how you respond to everything that happens in your environment, from climate change to childhood abuse.
You do not manifest disease merely by a defective gene, but by your epigenome. Epigenetic therapy, which is essentially the curing of disease by epigenetic manipulation, involves changing the instructions to your cells -- reactivating desirable genes and deactivating undesirable ones. This emerging field, now in its infancy, may represent the future of medicine.
You can begin to do this on your own, long before you manifest a disease, by encouraging your genes to express positive, disease-fighting behaviors in the first place by leading a healthy lifestyle.
To get started, please read through my comprehensive nutrition plan, which will give you tips and tools for eating healthy, dealing with stress and living a lifestyle that will support your epigenetic health, regardless of whether you were born with a high or low 2D-4D ratio.