Body secrets: What do genetic traits reveal about health?

Reduce your risk of health issues by reading your body's clues.
© MSN Healthy Living // © MSN Health

From hair color to arm length and earlobes, genetic traits may help predict the risk of certain health issues. Keep in mind, however, that one does not necessarily lead to the other, says Kevin R. Campbell, MD, FACC, cardiologist at Wake Heart and Vascular Associates, Raleigh, N.C.

"Many of these studies are not cause-and-effect but association. For example, there's no way an earlobe crease causes heart disease. Your genetics are your genetics, but you can modify everything else," Campbell said. If you have one of these predispositions, take stock in your lifestyle habits and do what you can to reduce your risk.

--By Linda Melone for MSN Healthy Living

1 of 14 Genetics (Adam Gault | Getty Images)

Redheads feel more pain

When Julianne Moore and Christina Hendricks visit the dentist, they may need a bit more numbing medication than blonde and dark-haired dental patients. A study published in the journal Anesthesiology (2005) showed a link to red hair and an increased sensitivity to pain.

"Some studies suggest that redheads may be more sensitive to thermal pain (temperature mediated) and potentially more resistant to the effect of subcutaneous anesthetics, as in when the dentist numbs you up," said David Maine, MD, director of the Center for Interventional Pain Medicine at Mercy Medical Center, Baltimore, Md. According to Maine, a mutation of the gene responsible for the redhead phenotype (what makes a redhead a redhead) may have some central function in the way the brain modulates pain sensitivity. If you're a redhead, let your doctor know if pain is a concern.

2 of 14 A woman with red hair (Kevin Russ/Getty Images)

Finger size ratio relates to verbal aggression

If you fly off the handle easily, check your fingers. The ratio of relative finger length may indicate a greater tendency for verbal aggression in adults, according to new research published in the Journal of Communications (Oct. 2012). In two studies, researchers measured the ratio of length of the index finger (2D) to the length of the ring finger (4D) of more than 600 volunteers. Those with a smaller 2D:4D ratio reported more verbal aggression behaviors than those with higher ratios.

"This difference relates to the exposure and receptivity of the fetus to testosterone in the womb," said Allison Shaw, PhD, assistant professor in the communication department at the University at Buffalo–State University of New York. Prior research also shows a link between this finger ratio and dominance, athletics and memory as well as physical aggression. "Keep in mind, however, that the amount of variation is so small — to hundreds of decimal places in millimeters — that it's really difficult to just look at someone's hands and predict who's going to be aggressive or not," said Shaw. So don't blame your fingers for your short temper.

3 of 14 Right hand (DAJ/Getty Images)

Lefties may be more prone to anxiety

Moody much? If you write with your left hand, you may be more prone to anxiety than some of your right-handed friends, studies show. Handedness gives clues to the way the brain is wired.

"In fact, there's evidence that people who make greater use of both hands, as opposed to dominantly using a single hand all the time, experience greater interaction or cross-talk between the left and right hemispheres of the brain," says Keith B. Lyle, PhD, researcher and psychologist at the University of Louisville, Ky.

This greater interaction may allow for increased flexibility in how people interpret and respond to anxiety-provoking situations. For example, people who use both hands may be able to see the positive aspects of anxiety-provoking situations or may be able to stop themselves from thinking about things that make them anxious, Lyle said. Anxious lefties may benefit from relaxation techniques such as mindfulness, meditation or yoga.

4 of 14 Ratio chart (Len DeLessio/Getty Images)

Shorter people may live longer

Tall people may need to stop with the short jokes, according to a study published in the Western Journal of Medicine (May, 2002). The study summarized findings of more than 25 years of research. Extensive data taken from animal studies show that people with smaller bodies often live longer and have delayed onset of chronic diseases. People living the longest include the Japanese, Hong Kong Chinese and Greeks, all shorter and weighing less than northern Europeans and North Americans.

While these studies suggest a shorter body size may link to longevity, other factors influencing longevity include body weight, regular exercise and various health practices. "You can still practice healthy lifestyle habits to reduce your risk (of early death and chronic disease)," said Campbell.

5 of 14 A short person and a tall person (Image Source/Getty Images)

Looking older may be a predictor of heart disease

Earlobe creases, a receding hairline, baldness and fatty deposits around the eyes not only age you, but may indicate health issues brewing, studies suggest. Many studies show that a linear wrinkle on one or both earlobes may be a predictor of cardiovascular events (i.e. heart attack), said Sameer Sayeed, MD, cardiologist with ColumbiaDoctors of Somers, N.Y. 

"Scientists offer no explanation for this link, but suggest it should be considered a factor in determining those patients who may be at a higher risk for cardiovascular disease. Wrinkles and gray hair in general are not associated with heart disease risk specifically, according to Sayeed. "However, studies found smokers are more susceptible to developing early wrinkles and skin changes."

Fatty deposits around the eyes may be due to a problem with cholesterol metabolism, either overproduction or inadequate removal from the body, said Sayeed, who recommends practicing a strict diet and exercise, taking preventative measures and closely monitoring cholesterol levels and blood pressure.

6 of 14 Adults (Tom Merton/Getty Images)

Finger length may link to prostate cancer risk

Finger length may provide more than a clue to verbal aggression. The amount of hormones in the womb also appears to influence finger length as it relates to prostate cancer risk, according to scientists at Britain's Warwick University and the Institute of Cancer Research (ICR). The 2010 study showed that men with longer index fingers than their ring fingers were one-third less likely to develop prostate cancer than men with the opposite pattern of finger lengths. The study showed that men with index and ring fingers of the same length had similar prostate cancer risk, but those with longer index fingers were 33 percent less likely to develop the disease.

Researchers believe being exposed to less testosterone in utero may influence two genes that control finger length and offer protection against prostate cancer later in life. If you're at risk, take measures to protect yourself: eat a low-fat diet high in fruits and vegetables, exercise most days of the week, drink green tea and go easy on alcohol, the Mayo Clinic recommends.

7 of 14 Long fingers (Adam Gault/Getty Images)

Women with short arms may be at a higher risk of Alzheimer's disease

How far can you throw? Women with short arms (less than 60 inches across when held parallel to the ground) may be 1½ times more likely to develop Alzheimer's disease than women with longer reaches, according to a study published in the journal Neurology (2008). Researchers believe early nutrient deficiencies in childhood may contribute to this link.

"An earlier study also showed that a shorter leg length related to a higher risk of dementia," said Jagan Pillai, MD, neurologist at the Cleveland Clinic Center for Brain Health who was not involved with the study. "There's an association, but what it actually means for individuals is hard to say. You can't generalize based on one measurement such as this."

The bottom line: If you have shorter arms don't be concerned unless other symptoms crop up (memory loss, mood or behavior changes, etc.), in which case check with your doctor for a thorough evaluation.

8 of 14 Woman with short arms (JGI/Jamie Grill/Getty Images)

Lack of a sense of smell and Parkinson's linked

Can't stop and smell the roses? Your sniffer could be trying to tell you something. A loss of the sense of smell may be a sign of the beginning of cognitive problems related to the onset of Parkinson's disease, according to a study published in the journal Brain (April 2012).

Researchers at Japan's Tohoku University found a link between hyposmia, a reduced ability to smell and detect odors, and Parkinson's disease. In the study, 24 out of 44 subjects had severe hyposmia. Three years later those with hyposmia showed greater cognitive and motor impairment than those without hyposmia and 42 percent developed dementia. None of the other subjects showed signs of dementia.

"A similar sense of smell problem has been noted in Alzheimer's disease," said Pillai. "But again, you can't diagnose on a single symptom." If you also experience tremors, rigid muscles and/or speech and writing changes see a doctor.

9 of 14 Nose (Michael Poehlman/Getty Images)

Big belly could increase dementia risk

Trouble fitting into your skinny jeans? Excess weight around your midsection — an apple shaped body — in mid-life could be a link to dementia and Alzheimer's later in life, according to a study published in the journal Neurology (March, 2008). The study showed that obese people with a large belly were three times more likely to be diagnosed with dementia in later years than those of normal weight and belly size. Diabetes, high cholesterol and high blood pressure that often accompany excess weight have all been linked to dementia, although we don't know the reason for the dementia, said Pillai. "You can't show a 'cause and effect' in a population study such as this, but you can show areas of concern to look into for public health."

Keep belly fat to a minimum with a high-fiber diet. A 2011 study published in the journal Obesity found a nearly four percent reduction in belly fat from a diet containing 10 grams of fiber daily.

10 of 14 Measuring around waist (Purestock/Getty Images)