Is Your Height Determined Only By Genetics And Therefore, Predetermined?

Height is one of the major physical features of humans.

Genetics is known to play a key role in determining our height. In fact, the genetic make-up of a child, marked by the height of both parents, is the first factor that is often taken into consideration while predicting his or her height in adulthood.

However, heredity is not the only factor that can influence the height of a person.

It would also be wrong to assume that a person will automatically attain the same height as that of his or her parents.

If you are eager to know how much of your genetics is involved in determining your height, keep reading. We will discuss various ways and the extent to which the genetic make-up can affect your height. We will also discuss the factors other than genetics that could increase or decrease your height.

The genetics of height

Genetics is among the most prominent factors that can contribute to how tall or short you will be.

As a rule of thumb, your height could be predicted based on the height of your parents. If both your parents are tall, you will naturally be expected to grow taller and vice versa.

If one of your parents is short and the other is tall, then your height would end up being somewhere near the average of the heights of your parents.

However, as said earlier, your genes are not the only predictors of your height. There could be instances wherein the child grows much taller than parents and other relatives. And, perhaps, the child may even be much shorter.

Some other factors play a role along with genetics and modify the influence of genes on your growth and height.

So, let us see how much of your height is actually determined by your genes or your parent’s height.

How much of your height is determined by genetics?

Scientists have estimated that about 80% of the height of an individual is determined by the genes. To be more specific, it is the DNA sequence variants the individual has inherited from parents that could play a role in deciding his or her height.

However, which of the genes or their variants can actually influence your height and how they affect the growth of the bones are understood only partially.

Some studies have revealed interesting results in this regard.

For example; some rare genetic mutations have been found to produce a dramatic effect on height. These include the specific variants in the FGFR3 gene that are known to increase the risk of a condition called achondroplasia. [1]

Achondroplasia is a rare disorder characterized by short stature. So, patients diagnosed with this condition may have a shorter stature in spite of their parents being taller. Now, when we talk about the influence of genetic on the height in patients with achondroplasia, we need to consider two different yet related aspects. [2]

Let me explain them in simple words.

It should be noted that achondroplasia is a genetic disorder, which means it occurs due to defective genetic variants. So, it can be said that achondroplasia or shorter height caused due to it is the result of the interplay of genetics on the patient’s growth.

This marks the role of genetics in determining the height of a person.

However, at the same time, short stature caused due to achondroplasia is in contrast to the belief that the child’s height is determined by the heights of parents. Because, in this case, the child with achondroplasia could be shorter even if the parents are taller or have average height.

So, this is a very tricky situation.

Though the genetics of parents does affect the height of a child to a large extent, the defects in the genes can further modify the effect of genes causing a shorter or taller stature depending on the variant.

In the case of achondroplasia, the effect of genes of parents would be negated by the effect of genetic variants which is why the child would be shorter in spite of having taller parents.

So, it would be right to say that genetics plays a huge role in determining your height though it is wrong to assume that the height of parents is the only genetic factor that needs to be considered for predicting the future height of a child.

The role of genetic variants in height

Other than the variants in the FGFR3 gene responsible for causing achondroplasia, more than seven hundred other variants have been discovered so far and many more are expected to be identified in the future.

Most of these genetic variants affect growth directly or indirectly by influencing the growth of the cartilage in growth plates in bones.

The growth plates are the areas in the long bones like the femur and tibia in the legs and humerus, radius, and ulna in the arms. It is in these growth plates that the new bone tissues responsible for increasing the height are produced.

The efficient growth of these tissues can lead to the lengthening of the bones as a child grows thus increasing his height.

Genetic variants that affect the growth of the cartilage in growth plates could affect the total length of the bones thus marking the role of genetics in influencing the height of a person.

Specific genes that influence your height

Other than the FGFR3 gene, hundreds of other genes have been identified to trigger the development of rare genetic disorders that could have an extreme effect on the height of a person.

These genetic variants and the conditions associated with them include:

FBN1

Children with genetic variants like FBN1 are likely to develop acromicric dysplasia, a condition characterized by short stature with short limbs, distinctive facial features, and stiff joints. [3]

Newborns with acromicric dysplasia are usually of normal height. However, slower growth over time might result in a shorter stature.

GH1

Genetic variations like GH1 could increase the risk of a condition called isolated growth hormone deficiency. It is caused due to the complete absence or severe shortage in the secretion of growth hormone, which is a protein necessary for the growth of the bones and tissues. [4]

Geleophysic dysplasia

Geleophysic dysplasia is another inherited condition that affects the growth of different tissues. This condition is characterized by abnormalities in the bones and joints as well as the functions of the heart and skin.

Patients with geleophysic dysplasia have shorter stature with short hands and feet due to the lack of proper growth of bones.

Marfan syndrome

Marfan syndrome is a genetic disorder known to affect the fibers called connective tissue, which support and anchor the organs of the body. Marfan syndrome may cause a shorter stature by affecting the development of bones.

GPC3

Genetic variants like GPC3 could increase the risk of Simpson-Golabi-Behmel syndrome, a condition that can affect the development of different tissues. It is more common in men than in women.

This condition is also classified as an overgrowth syndrome, as infants born with this disorder are considerably larger or taller than normal (macrosomia) at birth and continue to grow at an unusual rate.

EVC

Genetic variants like EVC could increase the risk of Ellis-van Creveld syndrome and Weyers acrofacial dysostosis.

Ellis-van Creveld syndrome refers to an inherited disorder that affects bone growth and results in short stature (dwarfism). Patients with this condition have short forearms and legs and a narrower chest with short ribs. [5]

Weyers acrofacial dysostosis also affects the development of the bones, teeth, and nails causing abnormalities related to growth.

Does the height gene skip a generation?

We have all seen it…. It is not uncommon for families of taller people to have a member who is short. We have also seen that some tall families often have that one member who seems like he or she does not belong. This peculiar observation is often attributed to the genes that can skip a generation.

Let me explain how.

Human Genetics is quite a complicated subject, which contains thousands of research studies and decades of research. The question we are trying to decode here is just how strong are the genes that determine the height of a person. To be more precise, we want to check whether the genes that increase stature can skip a generation such that the members of the same family can have a shorter or taller height in alternative generations.

It may not be like all members of a particular generation are tall and the next generation are short and so on. The skipping of the genes may affect any member of the generations. And this explains why sometimes we come across families of tall people having one or two members being shorter in height.

The genetic traits people receive from their parents are determined by the individual DNA strands of a person. Each strand carries specific human traits. And the specific physical characteristics of a person depend on the combination of these inherited traits that he or she may have received from the DNA of both the mother and the father.

Both your father and mother carry DNA that determines your height and how tall you would be, the color of your hair, your skin tone, etc. The parents carry these DNA strands with the traits they have. However, they may also carry certain traits that they have inherited from their ancestors, though they may not be evident in the forms of specific traits due to those particular genes begin recessive in nature.

It is only the dominant traits of the DNA that become evident by creating certain specific physical characteristic features.

So, just because you do not see specific ancestral traits in your physical appearance, it does not mean that you do not carry those genes.

They might just be recessive in your particular generation and may turn out to be dominant in the next generation causing your children to have a taller height based on those specific genes.

So, the taller ancestors you have are likely to determine your chances of having a tall stature. However, if you have even one ancestor who carried the genetic make-up of a shorter stature, you do have the possibility of ending up being short!

And this particular feature may, at times, skip a generation.

So, if your siblings are taller, it would mean the genes causing the short stature might have skipped a generation for them.

However, there are a few exceptions to this. In some such cases, it may not mean that the genes have necessarily “skipped” a generation. It might only suggest that this was how your genetic make-up was determined when the combination of different genes from your mother and father made up your own genetic make-up causing your stature to be shorter or taller.

So, it is hard to say for sure that the genes that determine height always skip a generation.

It may or may not work in that way. The shorter height of certain family members in comparison to others in the same family can be the result of the recessive genes skipping a generation. It can also be the result of the specific genetic traits the particular member has received from his or her mother and father.

The concept of polygenic inheritance

It should be noted that there are several height-associated genes, the functions of which remain unknown.

As height is determined by not one or two but multiple genetic variants, it is difficult to predict how tall a child would be with accuracy. This form of inheritance pattern is called polygenic inheritance.

The inheritance of multiple variants from the parents also explains why children often grow to be nearly as tall as their parents. However, different combinations of genetic variants cause siblings to have different heights.

Height is also influenced by other biological mechanisms like hormones that might be determined by the genetic variants. However, the exact role of these mechanisms is not fully understood.

Studying the dramatic effects of the mutated variants of these genes on growth and development could provide us with a better understanding of the role of genetics in height.

What does the latest research say about the influence of genes on height?

Genetics has been a subject of huge interest for researchers. The effect of genetic on the height of a child has been widely studied. The latest research has helped resolve the conflict in our understanding of the influence of genetics on height to some extent.

Studies of fraternal and identical twins have suggested that up to 80 percent of variations in height are determined by genetics. However, the genes responsible have eluded the researchers largely.

Now, through the largest such study ever, researchers have managed to amass genome data of nearly 4 million people that could account for a major share of ‘missing heritability’ at least for the people of European ancestry. This research has managed to identify thousands of DNA markers that appear to explain the influence of genetic variants on height.

The mystery of ‘missing heritability’ could be dated back to the late 2000s, during the period researchers had begun using new methods to scan human genomes for identifying markers linked to specific physical traits.

They expected that the results of genomewide studies would match scientific evidence from the genetics of families and twins and validate the effects of genes on height.

However, it turned out that each of these identified markers contributed to physical traits like height only slightly. For height, it was found that the 1^st 40 DNA markers could explain only 5% of its variations.

Later, a number of possible explanations were put forward, including rare gene variants that were missed by the genomewide studies. It was assumed that the twin studies were possibly wrong.

However, some researchers argued that they needed to detect more common variants with smaller effects and it was estimated that such variants, when considered together, might account for nearly 40 to 50 percent of the genetic component of human height.

Identifying such faint signals required in-depth studying of the DNA of a huge number of people.

Years later, DNA data of more than 700,000 people were pooled to support this theory. It was found that there were nearly 3300 common markers that could explain about 25% of the variations in height linked to genetics.

A large number of genomewide studies have further contributed to a DNA data of more than 4.1 million participants and helped to identify roughly 9900 common markers that have together accounted for 40% of the height variation.

Some other markers likely to be inherited or located nearby also account for another 10 percent of the genetically linked variability in height.

In 2019, further studies revealed that some rare variants carried by less than one percent of the population could explain an additional 30% of the variation in height. [6]

So, years of research and continued efforts by researchers have finally helped us understand that genetics does play a very huge role in determining the height of a person. [7]

It has shown that nearly 80% of our height could be determined by genetics.

In most individuals, the height is largely controlled by the combination of genetic variants each having a modest effect on the growth. Plus, environmental factors such as nutrition also contribute to the height of a person.

Let us now have a look at the factors other than genetics that could affect the growth and height of a child.

Factors other than genetics that influence height

Nutrition

Eating nutritious foods does not automatically make a child taller. Yet, getting adequate nutrition, especially proteins, is still considered critical for the proper development of children, especially during their growth years.

A diet containing wholesome nutritious foods would ensure the child grows up to the height dictated by his or her genes. On the other side, a poor diet that lacks adequate nutrients could lead to a shorter height compared to that of the parents.

Access to nutritious foods

Eating nutritious foods may not be possible for all families. Children belonging to a poor socioeconomic status might be at a risk of lack of proper growth and development due to inadequate access to nutrition and healthcare.

This, in turn, could lead to a shorter height.

Gender

You must have noticed that boys usually grow slower than girls initially due to the difference in their puberty milestones.

However, overall, adult males tend to be taller than adult females by an average of 5.5 inches or 14 centimeters. So, other than genetics, gender is also considered an important factor that influences height. [8]

Ethnicity

In most cases, ethnicity plays a vital role in adult height.

However, studies have shown that immigrant families moving to a location with better access to healthcare, nutritious foods, and employment opportunities are usually able to derive a substantial positive influence on the heights of the next generation.

This suggests that the differences in heights between ethnicities could be modified by the non-genetic environmental factors. [9]

Hormonal considerations

Hormones are essential for regulating the growth of the bones and other tissues in the body. These include human growth hormones, thyroid hormones, and sex hormones like estrogens and testosterone.

Abnormalities related to the secretion of these hormones could affect the growth of young girls and boys at puberty thus affecting their overall height.

This is why; children with hypothyroidism or pituitary gland disorders often grow shorter than the average height of their parents. [10]

Hormonal disorders can also cause a person to be taller than the average height. For example, children with gigantism that occurs due to the excessive secretion of human growth hormones by a pituitary gland tumor may grow very tall. [11]

In addition to these biological and genetic determinants, the height may also be influenced by factors like the nutritional status of the mother during pregnancy, whether the mother smoked during pregnancy, and her exposure to harmful toxic elements.

Conclusion

There is no doubt that genetics creates a huge influence on the height of an individual. Not just the genetic make-up of the parents or their heights, but even genetic variants can create a varied effect on the growth and development of children.

So, it wouldn’t be wrong to assume that the child of taller parents would grow to be taller and vice versa.

However, at the same time, we can not neglect the effect of environmental factors on the child’s growth and height.

A well-nourished, active, and healthy child is likely to grow taller than a child with poor dietary habits and inadequate health care. Socioeconomic factors like income, occupation, and education may also influence height.

Hence, it can be said that while genetic does play a vital role in determining the height of a person, several other factors come into the picture to modify the effects of genes and influence the final height.