Double Jointed

Can you bend your thumb to touch your wrist or extend your elbows past 180 degrees? In a family photo, do you and your relatives all flash a hitchhiker's thumbs up with the thumb bent slightly backward? If you spent time in elementary school impressing peers with how bendy your joints are, you could be double-jointed.

Double-jointedness is an interesting trait that often comes from a blend of genetic and external factors. You can learn whether you have genetic ties to it with an AncestryDNA + Traits test.

What Does It Mean to Be Double-Jointed?

People who are double-jointed don't literally have extra joints; rather, this term refers to people with joint hypermobility. They can extend their joints beyond what's considered the normal range of motion. When diagnosing hypermobility, doctors use a test called the Beighton score to check your flexibility across your back, elbows, knees, and hands.

Some people can extend slightly past the normal range. Others can contort their bodies significantly farther, appearing to nearly invert their joints. Hypermobility can present differently from person to person. Some people have peripheral hypermobility, which means it may be limited to the hands and feet. Others have localized hypermobility in a single joint or generalized hypermobility in multiple joints.

It's estimated that around 1 in 10 people are hypermobile.

Hypermobility occurs because your ligaments, the tissue that holds your joints together, are looser than those of the average person. For most people, it doesn't cause any issues, but hypermobility can be associated with:

• Pain in the joints and muscles
• Stiffness
• Fatigue
• Clumsiness and poor physical balance
• Injuries, such as dislocations and sprains

Regular exercise helps keep your joints supported and strong, which can help you avoid accidental injuries. Just remember to consider your hypermobility when choosing your workouts.

• Strength training, particularly with light weights and resistance bands, helps build muscles that provide additional joint stability.
• Low-impact aerobic exercises like biking, swimming, and walking can improve bone density.
• Avoid overstretching, which can worsen joint instability.

Double-Jointedness and Genetics

Joint hypermobility often runs in families, so if your parents or siblings are double-jointed, you are more likely to be as well. The AncestryDNA team has data supporting this finding. After asking over 500,000 people, "Are you double-jointed?" and comparing their answers to their genetic profiles, the team identified over 1,100 DNA markersDNA markers associated with this trait.

This information can be extrapolated further using a statistical tool called a polygenic risk score. This tool reveals how likely you are to have a trait or condition based on your DNA markers. Based on their findings, the team calculated that approximately 7% of the variation in whether people have double-jointedness is due to differences in their DNA.

What Else May Impact Joint Flexibility?

Several factors beyond your genetics can impact how flexible your joints are, including age and hormone fluctuations.

Notably, hormonal fluctuations during pregnancy can cause joints to loosen. During pregnancy, the ovaries and placenta produce higher levels of relaxin. This hormone relaxes the muscles, joints, and ligaments to prevent premature contractions and prepare the body for childbirth. It loosens the ligaments in the pelvis and softens the cervix to allow a full-term baby to pass through the birth canal. However, relaxin affects the entire body. Some people notice an increase in joint instability or general weakness during pregnancy.

Other hormones also play a role in affecting how hypermobile you may be. These often fluctuate with age, resulting in changes in flexibility.

• Progesterone: High levels of progesterone, often seen during the luteal phase of the menstrual cycle or during pregnancy, often increase instability in joints.
• Estrogen: Elevated estrogen levels often increase joint hypermobility. When levels drop during the menstrual cycle or menopause, some people with hypermobility notice increased joint stiffness.
• Testosterone: Low testosterone levels are associated with decreased muscle tone and joint instability. Male puberty, which increases testosterone levels, is often associated with a reduction in symptoms in hypermobile children.

Notable Facts About Hypermobility

Hypermobility can actually be an asset in athletes. In sports like baseball or javelin throwing, the increased range of motion in the shoulder joints can improve throwing velocity. Gymnasts, figure skaters, and dancers often use increased flexibility to their advantage for certain extreme positions. However, athletes must take care, as joint hypermobility is associated with increased injury rates.

Contortionists use hypermobility to push the human body to its limits. They often showcase their exceptionally flexible joints through jaw-dropping performances in circuses like the famed Cirque du Soleil, talent shows, trade shows, conferences, or other theatrical events.

Wondering whether your extra-bendy joints came from a family member? Take an AncestryDNA + Traits test to learn about how your genetics make you who you are. If you've already taken an AncestryDNA Origins test, review your traits results with your Ancestry subscription today.