Facts About Height - How Genes and Environment Determine How Tall You Grow

How Your Genes Determine Your Height

Your height is mostly determined by your genes. DNA from your parents is responsible for about 80% of your height. The other 20% comes from environmental factors like nutrition and health during childhood and adolescence. Genes affect your height in several ways:

Growth Hormones

Growth hormones produced in the pituitary gland, like human growth hormone (HGH), stimulate growth. The amount of HGH you produce is regulated by HGH genes. Mutations in these genes can lead to too much or too little growth hormone being made, resulting in abnormally short or tall height.

Growth Plates

Bones lengthen as you grow thanks to growth plates, which are areas of cartilage near the ends of bones. Growth plate cartilage eventually hardens into solid bone, stopping further lengthening. The timing of growth plate hardening is determined by genetic factors.

Height-Related Genes

Hundreds of genes are involved in growth and height. Researchers have identified certain genes associated with short and tall stature. For example, a mutation in the SHOX gene often causes short stature. Mutations in the NPR2 gene can lead to abnormally tall height.

Shorter People Have Lower Cancer Risk

Multiple studies show a correlation between height and cancer risk. For example, a 2018 study found the tallest 5% of women had a 37% higher risk of developing cancer than the shortest 5%. The risk was 20% higher for the tallest men compared to the shortest.

Researchers believe more cells in taller bodies may increase susceptibility to errors that cause cancer. The higher rates of growth factors like IGF-1 in taller people may also promote tumor growth.

Environment Affects Height During Childhood

While genetics are the main determinant of adult height, environmental factors play a large role in height during childhood and adolescence. Nutrition, hormones, and medical conditions can all affect growth:

Nutrition

Diets high in protein, minerals like calcium and phosphorus, and vitamins like vitamin D promote growth. Malnutrition leading to stunted growth remains a problem in developing countries.

Hormones

Thyroid and growth hormone deficiencies due to medical conditions can severely stunt growth if not treated properly before puberty. Conversely, an excess of these hormones could accelerate growth.

Chronic Diseases

Chronic inflammatory illnesses like Crohn's disease are associated with poor growth and short stature. Growth tends to improve with effective treatment of the underlying disease.

Shorter Adults Tend to Live Longer

Many studies show a correlation between shorter height in adulthood and longevity. For example, a 2020 study found men under 5 feet 3 inches lived an average of 4.95 years longer than taller men. Shorter women also had greater life expectancy.

Researchers propose that the same growth factors tied to height may accelerate aging when present at high levels. Shorter people tend to have lower levels of IGF-1 and growth hormones.

Height Can Affect Your Heart Health

Height seems to be associated with heart health in different ways for men versus women:

Shorter Men: Lower Heart Disease Risk

Studies consistently show shorter men have a lower risk of developing heart disease and suffering cardiac events like heart attacks. For example, one study found men under 5 feet 3 inches were 35% less likely to get heart disease.

Taller Women: Lower Heart Disease Risk

In contrast to men, taller women seem to have a lower cardiac risk. One study found women over 5 feet 9 inches had a 32% lower risk of heart disease compared to shorter women.

Researchers believe hormones like estrogen and testosterone that affect height may influence heart health differently between the sexes.

Growth Plate Injuries Can Affect Height

Growth plates help lengthen bones during childhood and adolescence. An injury that damages the growth plate can prematurely halt growth of that bone. Types of injuries that pose a risk include:

Fractures

A break that crosses through the growth plate or affects the region can damage it, stopping further bone lengthening. This is a particular concern in children with wrist, elbow, and knee fractures.

Dislocations

Forceful dislocations around areas like the hips and shoulders can also disrupt the growth plate. Prompt treatment is needed to minimize any lasting effects.

Tendon or Ligament Injuries

Damage to ligaments and tendons near growth plates, often due to sports-related injuries, can lead to abnormal bone growth and length discrepancies between limbs as a child matures.

Factors That Can Stunt Growth

While many factors influence your height as you grow, certain medical conditions and other issues can negatively impact growth if not addressed. These include:

Malnutrition

Diets chronically deficient in protein, calories, and nutrients like calcium and vitamin D can prevent children and teens from reaching their full growth potential.

Growth Hormone Deficiency

Insufficient growth hormone due to a pituitary gland issue stunts growth dramatically if not treated with growth hormone therapy before puberty.

Delayed Puberty

Puberty is a key growth period. Delayed puberty due to a health condition can therefore limit growth potential. But it usually picks up once the underlying issue is treated.

Chronic Illness

Serious chronic medical conditions like kidney disease, celiac disease, and asthma that are poorly controlled can impact growth. Effective management helps normalize it.

Medications

Certain medications like prednisone and drugs for ADHD can slow growth as a side effect. Doctors monitor height and may adjust dosages or recommend a growth hormone.

Being Tall May Have Advantages in Sports

Height can play a significant role in determining athletic ability and success in certain sports. In general, being tall is considered an advantage in:

Basketball

The average NBA player is around 6 feet 7 inches tall. Height is beneficial for key skills like rebounding and blocking shots.

Volleyball

Tall players excel at spiking and blocking at the net. The average height in women's volleyball is over 6 feet and over 6 feet 6 inches in the men's game.

Rowing

Tall rowers with long arms and legs in both sweep and scull rowing can take longer, more powerful strokes.

Swimming

A long torso, arms, and feet can boost speed in the pool. Michael Phelps and most elite swimmers tend to be well above average in height.

Shorter People May Excel in Some Sports

While height is an asset in many sports, being shorter can actually be beneficial in certain athletic pursuits. Some examples include:

Gymnastics

Short stature and compact size helps gymnasts control rotational skills while allowing for tighter, faster rotation.

Powerlifting

Having shorter limbs provides a mechanical advantage for squat, deadlift, and bench press in powerlifting competitions.

Martial Arts

A lower center of gravity in arts like wrestling, judo, and boxing allows smaller competitors to stay balanced and rooted.

Rodeo Events

The ability to climb quickly in and out of steer wrestling and calf roping positions favors more compact cowboys.

Factors That Help You Reach Your Height Potential

While your genes play the biggest role, certain environmental factors during childhood, puberty and adolescence can help you maximize your height potential:

Proper Nutrition

Getting sufficient calories, protein, vitamins and minerals like calcium and vitamin D supports growth.

Regular Exercise

Exercise and sports improve growth hormone secretion and keep bones and muscles strong.

Adequate Sleep

Growth hormone release peaks during deep sleep. Getting enough quality rest fuels growth.

Medical Care

Treating underlying conditions that affect height and monitoring growth patterns ensures any issues are addressed early.

Height Differences Between Men and Women

On average, men tend to be taller than women. Some key facts about the height differences between males and females include:

Average Adult Heights

According to CDC data, the average height for American men 20 years and older is 5 feet 9 inches. For women, it is 5 feet 4 inches.

Puberty Accounts for Much of the Difference

Before puberty, average height for boys and girls is similar. The peak growth spurt during puberty accounts for much of the gender difference in final adult height.

Estrogen Plays a Role

Estrogen levels rise much faster in girls during puberty, triggering growth plate fusion and limiting height. Testosterone extends the growth period for boys.

Shorter Women May Live Longer

As discussed previously, shorter stature in adulthood seems to increase longevity for women. This effect is not seen as strongly in men.

Measuring Height Accurately

To get an accurate reading of height, here are some tips for proper measurement technique:

Use a Stadiometer

Stadiometers are fixed height rods with a sliding horizontal arm to form a right angle and flat base to stand on. This provides a consistent, precise measurement.

Remove Shoes

For an accurate height, shoes should be removed, along with any thick socks or slippers that could interfere with the measurement.

Stand Up Straight

The person being measured should stand with their back to the stadiometer, feet flat on the base, and looking straight ahead. Arms should hang freely with shoulders relaxed.

Lower the Arm Snugly

The horizontal arm is lowered gently until it is flush against the head to compress the hair. Excess force should not be used.

Record to the Nearest 1/8 Inch

Height generally does not need to be precise to the nearest millimeter. Recording height to the nearest 1/8 inch or 0.1 cm is sufficient in most cases.

Normal Height Range for Children

While children follow individual growth curves, these general ranges represent the normal spectrum of heights according to age:

Newborns

The average newborn is 19 to 21 inches long. Length between 18 to 22 inches is common.

6 Months

Average length is about 24 to 28 inches by 6 months. Normal range is 22 to 30 inches.

1 Year

Most 1-year-olds measure between 28 to 34 inches tall. Normal is considered 25 to 37 inches.

2 Years

Average height is 32 to 37 inches at age 2. Normal range spans 29 to 40 inches.

5 Years

Children tend to measure 37 to 45 inches around age 5. Normal is 34 to 46 inches.

Tracking Growth to Catch Potential Problems

Checking height at regular well-child visits allows tracking growth trends over time. Doctors can then identify potential issues like:

delayed growth

Falling significantly below the normal height range warrants evaluation for underlying causes like growth hormone issues, poor nutrition, celiac disease, and other factors stunting growth.

excessive growth velocity

Significantly outpacing peers in height gain month-to-month or year-to-year may indicate a hormone disorder accelerating growth abnormally.

disproportionate limbs

If arm and leg lengths or the torso appear out of proportion to overall height, it could reflect bone growth problems from weak muscles, scoliosis, or prior injury affecting the growth plates.

Adult Height Predictors in Children

While not definitively accurate, doctors can estimate a childs future adult height using different methods:

Mid-Parental Height Method

Adding the mothers and fathers heights, then dividing by two and adjusting for sex often provides a rough predicted adult height range.

Bone Age Assessments

X-rays to determine bone maturity based on development can help predict remaining growth from the child's current bone age.

Growth Velocity

Tracking past growth rates on growth curves provides guidance for estimating the rate of future growth.

When to Seek Medical Evaluation

Talk to your childs doctor about further evaluation for short or tall stature that:

Persists Beyond the Normal Range

Falls outside the normal height parameters for age, especially if persistent over several years and impacting growth curve percentiles.

Impacts Social and Emotional Health

Causes significant insecurity or social stress for a child or affects their emotional well-being and functioning.

Runs in Families

Height that is exceptionally short or tall such that it stands out in the context of the familys statures on both maternal and paternal sides.

Is Associated with Other Symptoms

Along with unusual growth patterns, presents with symptoms like headaches, fatigue, disproportionate body parts, developmental delays, or other concerning systemic issues.

Treatment Options for Unusually Short or Tall Height

Various treatment approaches exist for atypical heights outside the normal range:

Growth Hormone Therapy

Synthetic growth hormone injections can increase height in those with a true growth hormone deficiency.

Testosterone for Delayed Puberty

Testosterone treatment may help spur growth in boys with extremely late puberty.

Surgical Lengthening

For severe short stature, surgically implanting devices to gradually lengthen bones through distraction osteogenesis can add several inches of height.

Growth Inhibition

For excessively tall children, hormone therapy may be used to accelerate growth plate fusion and slow further growth.

Factors Impacting Height During Development

The main factors that can influence your height as you grow up include:

Genetics

Genes provide the blueprint that largely determines your growth potential and final height.

Nutrition

Adequate calories, protein, vitamins and minerals, particularly calcium and vitamin D, are essential for optimal growth.

Hormones

Growth hormone and sex hormones like estrogen and testosterone must be present in proper balance.

Medical Conditions

Chronic illness or disease can restrict growth. Effective management can restore normal height gain.

Environmental Toxins

Lead exposure and smoking have been linked to slightly shorter heights due to toxic effects on growth.

Tips for Supporting Healthy Growth

To help your child reach their full height potential as they grow, aim for:

A wholesome, nutrient-rich diet with plenty of protein,

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.