Hypermobility is usually caused by a mix of genetic, structural, and sometimes hormonal or disease-related factors that make joints looser and tissues more stretchy than average. For many people it is a benign inherited trait, but in others it is part of a wider connective tissue disorder such as hypermobile Ehlers–Danlos syndrome or Marfan syndrome.

What hypermobility actually is

Hypermobility means one or more joints move beyond the “normal” range expected for age and sex, either on their own or when pushed.

Some people are just generally “bendy” everywhere, while others only have a few especially loose joints, like shoulders, knees, or fingers.

Main causes of hypermobility

The underlying causes can be grouped into a few broad categories:

  • Genetic/connective tissue factors
    • Hypermobility often runs in families, suggesting a strong inherited component.
* In many, the core issue is **faulty collagen or other connective tissue proteins** , which makes ligaments and joint capsules less stiff and more stretchy.

* Heritable disorders that can feature marked hypermobility include:
  * Hypermobile Ehlers–Danlos syndrome (hEDS) and other EDS types (collagen and connective tissue disorders)

  * Marfan and Loeys–Dietz syndromes (connective tissue disorders affecting the skeleton, eyes, heart, and blood vessels)

  * Some genetic/developmental conditions such as Down syndrome, osteogenesis imperfecta, Morquio syndrome, and others.
  • Bone and joint shape
    • The way the ends of bones and sockets are shaped can increase laxity: for example, shallow sockets or altered joint angles allow more movement and easier subluxation or dislocation.
* This structural setup can make someone look “double-jointed” even without a major connective tissue disorder.
  • Ligament and soft-tissue laxity
    • Ligaments that are weak, stretched, or unusually elastic allow joints to move further than normal.
* Changes in elastin (the protein that gives tissues stretch) and collagen balance can make ligaments and capsules looser and less able to restrain motion.
  • Age, sex, hormones, and ethnicity
    • Children and teenagers tend to be more hypermobile; laxity usually decreases with age as tissues stiffen.
* Hypermobility is more common in females and in some ethnic groups, suggesting both hormonal and genetic influences.

* Hormones such as estrogen and pregnancy-related hormones can temporarily increase joint laxity, especially during pregnancy.
  • Training, lifestyle, and acquired causes
    • Repeated stretching or specialized training (e.g., dancers, gymnasts, contortionists) can increase the range of motion in specific joints over time.
* Some medical issues such as inflammatory or degenerative joint diseases, endocrine disorders (for example, hypothyroidism), and malnutrition in children can contribute to or exaggerate hypermobility in certain people.

* Past trauma, surgery, or joint damage can leave individual joints more unstable and hypermobile than before.
  • Neuromuscular and proprioceptive factors
    • Low muscle tone or strength can reduce active support around a joint, making any existing laxity more obvious.
* Poor proprioception (the body’s sense of joint position) may lead people to move into end-range positions more often, reinforcing hypermobile patterns.

When hypermobility is part of a syndrome

In many people, hypermobility is “isolated” and mostly harmless, sometimes called benign joint hypermobility.

In others, it falls under Hypermobility Spectrum Disorders (HSD) or hypermobile Ehlers–Danlos syndrome (hEDS), which may also involve pain, frequent sprains or dislocations, fatigue, skin changes, gut symptoms, and autonomic issues.

Some key points about these broader syndromes:

  • They are usually genetic and often present from childhood or adolescence.
  • Many still lack a single clear gene test (especially hEDS), so diagnosis is clinical and based on detailed criteria.
  • They can coexist with other conditions like fibromyalgia, chronic fatigue, and dysautonomia, which can complicate the picture.

Why some people only get symptoms later

Even if someone has always been hypermobile, pain and problems may only appear later in life:

  • Accumulated micro-injuries, sprains, and subluxations can gradually irritate joints, leading to chronic pain.
  • Changing hormones (puberty, pregnancy, menopause) or major illness can unmask or worsen symptoms.
  • Reduced physical conditioning (less muscle support, more sedentary time) can make joints feel more unstable and sore.

In simple terms: hypermobility comes from how your body is built and wired – your genes, your connective tissue, and your joint shapes – and those basics are then modified by age, hormones, training, and health over time.

TL;DR:
Most hypermobility is inherited and linked to naturally looser connective tissues and specific joint shapes, sometimes as part of a connective tissue syndrome like hEDS or Marfan syndrome. Other influences such as age, sex, hormones, training, injuries, and certain diseases can increase or reveal joint laxity and turn a “bendy” body into one that hurts or injures more easily.

Information gathered from public forums or data available on the internet and portrayed here.