Why Do Some People Have Genetically Long Eyelashes?

Have you ever wondered why some people naturally have more noticeable eyelashes than others? Genetics can certainly play a part, but lash length isn’t determined by genes alone. Age, hormones, overall health, the natural lash growth cycle, and even specific medications can all have an impact on how lashes grow.

In this article, we’ll take a closer look at the genetics behind eyelash length, how the natural growth cycle affects your lashes, and why some people just have longer-looking lashes than others.

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Although we all have our own opinion as to what constitutes long eyelashes and what doesn’t, there is a length that’s officially considered as long eyelashes. That is 12mm and it is often known as eyelash trichomegaly. So, it’s best to start there.

How Do Eyelashes Normally Grow?

Just like the hair on your head, eyelashes follow a natural growth cycle. Each lash moves through three main stages: the anagen (growth) phase, the catagen (transition) phase, and the telogen (resting and shedding) phase. Once an old lash sheds, a new one eventually grows in its place.

The length of your lashes is determined in part by how long they remain in the active growth phase and how quickly they grow before transitioning to the next stage. These patterns vary naturally from person to person and are influenced by genetics, age, hormones, and overall health.

That is why some people's lashes are naturally more noticeable or longer than others. In most cases, this variation is completely normal and simply reflects your unique lash growth pattern.

What Exactly is Eyelash Trichomegaly?

Eyelash trichomegaly is a medical term that refers to an unusual increase in length, thickness, pigmentation, or curl. Rather than simply describing naturally visible lashes, the term is typically used when lash growth is particularly noticeable.

Trichomegaly is uncommon and can have several causes. It can be inherited, coexist with other congenital or acquired conditions, or be a side effect of certain medications.

Congenital Trichomegaly

Congenital trichomegaly is defined as unusually prominent eyelashes that are present at birth or develop early in life. In some rare cases, it can coexist with genetic conditions like Cornelia de Lange syndrome or Oliver-McFarlane syndrome.

However, naturally long or thick lashes do not usually indicate an underlying medical condition. When trichomegaly is associated with a genetic syndrome, it typically appears alongside other distinctive symptoms rather than being the only noticeable feature.

For many people, naturally longer lashes are simply a feature of their unique appearance or a family trait.

What About Familial Trichomegaly?

Sometimes, unusually long or thick eyelashes simply run in the family. Several family members may share this trait without exhibiting any other symptoms or having an underlying medical condition.

Researchers studying families with this type of inherited lash growth discovered genetic differences that could play a role, including variants in a gene called FGF5.

So, when similar lash characteristics appear across generations, they may simply be part of the family's genetic makeup rather than an indication of a problem.

What is FGF5 and What Does it Have to Do with Eyelash Length?

FGF5 stands for Fibroblast Growth Factor 5, a gene that regulates the hair growth cycle. It helps signal when actively growing hair should move on to the next stage of its cycle, which can affect how long the hair grows before stopping.

Certain changes in the FGF5 gene have been linked to longer hair and eyelashes because they may prolong the growth phase. However, FGF5 is only one piece of the puzzle. Eyelash length is a complex trait influenced by several genes and other biological factors.

How Can FGF5 Variants Be Inherited?

We inherit copies of the FGF5 gene from our parents, and certain variants can influence how it functions. Some rare FGF5 variants have been linked to longer hair and eyelashes, especially when a person inherits the variants from both parents.

However, genetics isn't always as simple as inheriting one particular gene change. Different forms of trichomegaly can have different causes and inheritance patterns, which is why FGF5 shouldn't be considered the single explanation for unusually prominent lashes.

What about Trichomegaly and Medication?

Certain medications can promote eyelash growth, but this is a rare cause of unusually long lashes and usually occurs as a side effect of another medical condition.

One example is latanoprost, a prescription medication used to reduce intraocular pressure in people with glaucoma and other eye conditions. Because the medication affects the hair growth cycle, it may cause increased eyelash length, thickness, and pigmentation.

Other medications, such as erlotinib, a cancer treatment, have also been linked to changes in eyelash growth. These are medical examples, rather than common explanations for naturally long lashes.

Importantly, prescription medications such as latanoprost should not be used simply to make eyelashes grow longer. They should only be used as prescribed and with the supervision of a qualified healthcare professional.

Conclusion

So, now you know why some people naturally have more noticeable lashes than others. Genetics and the natural lash growth cycle can both influence their appearance, but health conditions and certain medications can also have an impact on lash growth in less common cases.

For most people, naturally long lashes are simply a normal inherited trait and nothing to worry about. However, if you notice a sudden or unexplained change in the length, thickness, or growth of your eyelashes, especially alongside other symptoms, it’s worth discussing it with a healthcare professional.