Learn how genetics might affect the eyelashes you have
We all want long, thick, upward-curling eyelashes. At least that seems to be considered an ideal feature for beauty, and has been since the beginning of recorded history. If we weren’t fortunate enough to be blessed with them naturally, we will use all the tricks we know to try to achieve the appearance of long eyelashes. We use mascara, false eyelashes, lash curlers, growth serum, or even extensions. But for those who naturally possess those long, beautiful eyelashes, how were they lucky enough to get them? Are long eyelashes a genetic trait?
How Long Should Our Eyelashes Be?
Eyelashes are not only beautiful, they serve an important function. Eyelashes sweep up and down when we blink, and this helps to keep dust particles in the air around us from settling into our eyes. Also, the upward curve of our eyelashes helps to catch drops of moisture and keep them from disrupting our vision. They also provide some sun protection, kind of like little eye-awnings.
According to the Georgia Institute of Technology, for twenty-two species of mammals, including humans, ideal eyelash length is around one-third the width of the eye. This study included eyelash models and a wind tunnel, and it showed that this length is actually ideal for performing the tasks that our eyelashes are meant to accomplish. They function very well to keep the eye surface moist and free of dust particles. Denser eyelashes, or those with less space between lash follicles, naturally function even better at keeping out dust and moisture than sparser eyelashes.
Surprisingly, eyelashes with lengths longer than one-third the width of the eye do not perform as well. Lashes that are too long can actually direct particles toward the eye, rather than keeping them out, causing long-lashed people to suffer more eye irritation. Though they look pretty while blinking their eyes more to compensate!
Eyelashes as a Genetic Trait
Because we are the product of two parents, all of our genes come in pairs, or alleles. In each pair we have one gene from each parent, and the gene from each parent may be a dominant trait or a recessive. A dominant gene will result in offspring showing that particular trait, though they will still carry the recessive gene and pass it on to their children. Recessive genes will result in offspring with that particular characteristic only if the recessive characteristic is in both genes in the allele, meaning one recessive gene from each parent was inherited.
There are two basic eyelash types: long or short. The good news is that the long eyelash trait that most of us covet is the dominant trait. This means that if one parent has long eyelashes and the other parent has short, children are more likely to inherit the long eyelashes. A gene square diagram will show that the odds are two out of three for offspring to inherit the long eyelashes over the short, which only happens if a child inherits two recessive genes for shorter eyelashes.
Curly Lashes vs Straight
When it comes to eyelashes being either straight or upward curling, ethnicity plays a role. Straight eyelashes are much more common in Asian people and those of Spanish and Eastern European descent than in other ethnic groups.
The growth of straight eyelashes is caused by a lack of double eyelid creases. Having a monolid will cause lashes to grow downward and out, rather than out and upwards. Of course, if you have stick-straight eyelashes and wish to have curling ones, you can always try an eyelash curler. Heating your eyelash curler with a blow dryer or hot water first can help the curl to last all day.
Double Rows of Eyelashes
Having an extra row of eyelashes is less common than long eyelashes, but it is also a dominant trait that is actually the result of a gene mutation error of the 16th chromosome. This can have two results. It can be quite beautiful, in cases like the famous, flirtatiously dark and thick eyelashes of Elizabeth Taylor, but it can also cause some irritation, as the extra eyelashes are often on the eye’s waterline and can sometimes turn toward the eye.
Eyelashes are hair, but they are different from all other body hairs. Eyelashes are darker than all other hairs on our bodies, even for those who are blonde. They are also the very last hairs on the human body to turn gray or white. Like all hair, our eyelashes can fall out, and get replaced over time.
While no one likes to see a precious eyelash fall out—even though it means we can make a wish—the good news is that it only takes about six weeks for an eyelash to grow back.