Buzz
A person's distinct physical appearance is the combined result of traits passed down from previous generations, blended with the characteristics of their chosen partners, which are then carried forward to the next generation. While it's widely known that traits like skin color, eye color, and hair color are inherited, there are many other inherited traits that may not always be beneficial. Genetic diseases, for example, are passed down, and we often wish these could be avoided.
However, genetics also has its more amusing side. Some traits that have been handed down through generations, despite offering little or no evolutionary advantage, continue to survive.
And yet, they do spark interesting conversations.
10. The ability to roll your tongue
Approximately two-thirds of people can effortlessly roll each side of their tongue into a tube shape, while the remaining third are left with flat tongues. This seemingly trivial genetic trait was first observed by geneticist Alfred Sturtevant in 1940. He argued that tongue-rolling was a Mendelian trait, passed down from just one parent rather than a combination from both, which explains its widespread occurrence. Other Mendelian traits include eye color and freckles.
Unlike freckles, however, tongue rolling can sometimes be learned. Non-rollers can train themselves to form a tube shape with their tongue after much practice, though it's unclear why anyone would bother. A study conducted by Delaware’s Department of Biological Sciences, involving 33 non-rollers, revealed that after a month of diligent practice, only one person managed to achieve the ‘skill’. Perhaps the other 32 simply weren't motivated enough?
Interestingly, the ability to roll your tongue isn't always purely genetic. Research has shown that non-genetic factors can influence whether someone can curl their tongue. Moreover, there are a few unlucky individuals who aren’t quite rollers or non-rollers, able to curl their tongues just slightly.
Oddities.
9. Hairy knuckles
If you notice hair growing on the upper part of your fingers, between the knuckles (at the mid-phalangeal joint), it might not be a sign of your inner Jekyll and Hyde, but rather a genetic trait passed down to you.
Anthropologists have spent nearly a century studying these peculiar hairs. One can only wonder how long that research took. This hair growth most commonly appears on the fourth finger (the ring finger) and never on the thumbs. It is also more frequently observed among Caucasians, although the reason for this remains unclear.
Researchers suggest that prenatal exposure to androgens, hormones that influence the development of male traits, could be responsible for this phenomenon. The trait is considered dominant, meaning it needs to be present in one or both parents. However, the specific gene responsible for hirsute fingers has yet to be identified.
Perhaps there’s a Nobel Prize waiting for whoever uncovers it?
8. Hand clasping
Though we might not always notice it, every time we clasp our hands, we are following a hand-clasping habit passed down from our ancestors. Chances are, at least one of our parents shares this same hand-folding style. This would be more impressive if there were many possible ways to clasp, but essentially, you can either place your right hand over your left or vice versa.
Given that there are only two options, it’s a safe guess that one of our parents clasps their hands just as we do. But researchers have gone to great lengths to study this ‘phenomenon,’ and their findings reveal that around 55% of people clasp their hands with the left hand on top, 44% with the right hand on top, and 1% don’t have a preference at all.
Unsatisfied with these results, researchers dug deeper into the family genetics of their subjects and discovered that hand-clasping preference follows a genetic inheritance pattern similar to left- or right-handedness. However, the preference for hand-clasping was not linked to which hand was dominant.
Spooky, right?
The research also uncovered a connection between hand-clasping and arm-folding preferences, as well as the curious finding that menstruating women often change their hand-clasping preference.
We're not even going to go there with that joke.
7. Free Earlobes
If you really stop and examine an ear, it can start to look a bit strange. Ears come in countless shapes and sizes, and you might think that the ears you inherit are simply a matter of luck. While the shape, size, and how much they stick out might be a matter of chance, it turns out that your earlobes are actually determined by your genetics.
Ears are one of a kind. It’s believed that no two ears are exactly the same (except, of course, the one on the other side of your head). The shape of the earlobe is determined by an allele gene, and as with all genes, we inherit two copies, one from each parent.
Though earlobes may seem pointless—other than serving as a place to hang jewelry—they are thought to help keep our ears warm thanks to their rich blood supply. They might even aid in maintaining our balance. The earlobe also contains a surprisingly large number of nerve endings, which is part of why it’s often considered an erogenous zone.
There are two main types of earlobes: free and attached. Free earlobes, the more common type, have a portion of skin that hangs below where the lobe attaches to the side of the head. It’s believed that free earlobes are the result of a dominant gene. Attached earlobes, on the other hand, are typically smaller and do not hang freely. They’re thought to be caused by a recessive gene. Despite the differences, there’s no known advantage to having either type of earlobe.
Because, let’s face it, ears are just strange.
6. Sneezing
Most sneezes, of course, aren’t determined by our genes. More often than not, they’re the result of a virus, allergies, or environmental factors, like being in a dusty room. However, there are some types of sneezing that can be genetically linked.
Some individuals have an inherited sneeze reflex that’s commonly triggered by bright light, though other causes can set it off too. This light-sensitive sneeze reflex, humorously called ACHOO syndrome (short for “Autosomal dominant Compelling Helio-Ophthalmic Outburst”—because “Genetically Induced Sneezing” just didn’t have the same punch), is thought to affect between 11% and 35% of people, with Caucasian females being the most affected.
Sneezing is a dominant trait, meaning that if one of your parents has the syndrome, there’s a 50% chance that you’ll inherit it too. However, the syndrome often goes unnoticed since sneezing is such a common occurrence. The exact gene responsible for triggering these sneezing fits hasn’t been pinpointed yet. For those affected, stepping into bright light could cause them to sneeze up to 40 times, but after a while, their body adjusts.
Currently, there’s no known treatment for the condition, although it can be managed with tissues.
5. A Bent Pinkie Finger
While not always due to genetics, a pinkie that appears to bow outwards is often considered an inherited trait. If you’re curious about the reason your finger seems a little crooked, it might be worth taking a look at your parents’ hands. If one of your parents has a bent pinkie, there’s a 50% chance that you could inherit it.
As with many so-called ‘conditions’, a bent finger could also stem from non-genetic causes, such as injury or disease. Researchers have also questioned what degree of ‘bentness’ makes a finger qualify as ‘bent’. Is it the angle of the bend that’s inherited, or is it just the fact that the finger is bent?
Clearly, more research is needed in this important field. The positive side is that corrective surgery is available should the angle of the bent finger become extreme.
4. A Widow’s Peak
It’s widely known that male pattern baldness can be linked to genes passed down from the mother. The X chromosome from the mother may carry a genetic predisposition for baldness, though it’s not the sole cause. Genes from the father can also play a role, but there’s a higher likelihood that the ‘baldness gene’ came from the mother if baldness occurs before age 40. Environmental factors, such as smoking and drinking, can also contribute to hair loss.
When it comes to a widow’s peak, however, the genetic link is much clearer. This distinctive V-shaped hairline is a dominant trait that can be inherited from either parent, and both men and women can have a widow’s peak, although it tends to be less noticeable in women because they generally don’t experience hair loss.
The ‘peak’ refers to the triangular hairline shape, which becomes more prominent with hair loss. While the widow’s peak is inherited, it doesn’t necessarily mean baldness will follow as a result.
Although, it likely will.
3. Tone Deafness
Tone deafness, along with its opposite, perfect pitch, can both be inherited traits.
Referred to as Congenital Amusia (perhaps because it makes people chuckle when you attempt to sing), inherited tone deafness is a condition where individuals are unable to recognize or distinguish between musical pieces. They cannot identify a song based on its melody alone, nor can they tell when a song is off-key. Research has also shown that those with this condition cannot detect a ‘bum note,’ a skill that even most babies can demonstrate.
While tone deafness can occasionally result from a brain injury, the vast majority of people who are tone deaf exhibit no other symptoms and face no real difficulties, except for being banned from Karaoke. Which, to be honest, isn’t much of a hardship.
Specifically, individuals with congenital amusia are unable to recognize when they are singing off-key themselves. Between 70 and 80% of people who are tone deaf inherit this condition, and it is estimated that around 4% of the population is affected.
Which, perhaps, sheds light on why dubstep has become so popular.
2. A Shock of White Hair
A white streak of hair, typically near the front of the head, can be an inherited trait. This patch, known as poliosis, or the 'Mallen Streak' after a family in a TV show who all sported the same white streak, can affect not only the hair but also the eyebrows, skin, and even eyelashes.
When the condition isn't genetic, such patches may indicate an illness. However, despite widespread myths, hair cannot turn white instantly due to shock.
For individuals with inherited poliosis, there are no associated conditions or disadvantages, except for a unique appearance, often adored by mysterious women with a fondness for spotted dogs.
1. A Long Second Toe
‘Morton’s toe’ refers to an inherited trait where the second toe exceeds the size of the big toe, and in some cases, the third toe is also elongated. The exact percentage of people affected by this condition varies, but it is estimated to impact anywhere between 3% and 20% of the population. The condition is named after an orthopedic surgeon, not a man with unusually long toes.
Morton theorized that the longer toe might be a vestige from a time when our primate ancestors had a 'grasping toe.' However, this theory remains unproven. Shoe-fitters often refer to this toe shape as the ‘Greek foot,’ after the classical sculptures of Ancient Greece where the longer second toe was considered aesthetically ideal. The Statue of Liberty is said to have a Morton’s toe.
It remains unknown whether she inherited this trait from her mother or her father.
