When being tickled, do you find yourself falling into uncontrollable laughter or not reacting at all? Tickling isn't always a laughing matter, but the reaction is often involuntary—one seen across multiple animal species, including humans. So, why are people ticklish?

Whether tickling facilitates social bonding or is a protective innate response—two of the scientific theories—there appears to be some sort of relation between being ticklish and genetics. An AncestryDNA^® + Traits test can help shine a light on whether your response to tickles is influenced by your DNA.

Is Everyone Sensitive to Tickles?

The sensitivity a person has to being tickled can be influenced by all sorts of factors. A person’s reaction to a tickle may also vary based on the two types of tickling:

1. Knismesis is a soft tickling caused by a light skin irritant—like a hair, a feather, or a blade of grass. Being tickled that way could result in a shiver or jerking away.
2. Gargalesis is intense tickling, like squeezing and poking. It often results in unrestrained involuntary laughter.

In addition, there’s a considerable range on the scale of tickling reactions: one individual might experience whole body spasms, another may squirm a bit, while a third could show nothing but unflinching calm. The involuntary physical movement (or lack thereof) may also be accompanied by loud laughter, quiet giggles, or silence. This variability has led scientists to theorise around a biological purpose of ticklishness. Scientists can't yet agree on one.

The most common ticklish spots on your body include your neck, armpits, stomach, sides, and feet.

Tickles and Genetics

AncestryDNA scientists, seeking to expand the understanding of genetics and ticklishness, asked over 496,000 people, “Are you ticklish?” By comparing responses to their genetic makeup, the AncestryDNA team found over 4,500 specific DNA markers that influence ticklishness.

The scientists also calculated a polygenic risk score, which allows them to see if you have a genetic inclination towards ticklishness. However, having the genetic markers associated with being ticklish doesn’t mean you’ll automatically burst into laughter at the slightest stimuli. In fact, only about 4% of the variation in ticklishness can be explained by differences in genetics. Environmental factors have a significantly higher influence on whether or not someone is ticklish—explaining 96% of the variation in the population.

What Else Do Scientists Say About Ticklishness?

Many factors beyond genetics can influence your response to being tickled. Any one of the following elements—and combination of them—could heighten your reaction, dampen, or mute your sense of ticklishness.

• Mood: Whether you’re happy, sad, or mad may impact your tickle response. Being in a positive mood will probably make you more receptive to tickles, yet being anxious can also increase your ticklishness. Moods like frustration, apathy, or anger are more likely to squash a joyful tickle reaction.
• Personal relationship: If you know the person well and there’s a high level of trust, you’re more likely to have a positive response to tickling. But if you were teased as a child by tickling, then you may be less receptive to it as an adult.
• Skin sensitivity: Physical sensitivity can play a big role in whether being tickled is pleasant or disliked. Some people have a condition known as hyperesthesia, which causes increased sensitivity and can affect the sense of touch. When people experience heightened sensitivity to touch, tickling can feel painful.

Why Can’t We Tickle Ourselves?

Most people can’t tickle themselves. As an example, we know when we’re brushing a feather across the bottoms of our own feet, but when someone else does it, we can’t anticipate the level of pressure or frequency. Some researchers think that this is because self-tickling doesn’t have the element of surprise. The brain knows when a movement is self-produced, so it responds differently than when the movement is unpredictable.

The brain’s response to tickling is complex. MRI studies have found more than seven parts of the brain jump into action after tickling. One zone—the hypothalamus—may be connected to the involuntary laughter that being tickled creates, as it controls emotional responses. Other studies have shown that self-produced tactile stimuli, such as self-tickling, activate the somatosensory cortex and anterior cingulate cortex at a lower level.

If you're curious to discover more about your genetics and how they contribute to who you are, AncestryDNA^® + Traits can help provide insight. Discover whether you have genes associated with ticklishness, sun sneezing, and other physical and behavioural traits. If you already have your AncestryDNA results, you can explore your genetic connection to tickle genes and other personal traits that you may have inherited with a membership to Ancestry^®.

 

References

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“Hyperesthesia.” Cleveland Clinic. Accessed September 5, 2024. https://my.clevelandclinic.org/health/symptoms/hyperesthesia.

Leavens, David A. and Kim A. Bard. “Tickling.” Current Biology. February 8, 2016. https://doi.org/10.1016/j.cub.2015.06.014.

McDermott, Annette. “What Causes the Tickle Response?” Healthline. December 22, 2016. https://www.healthline.com/health/why-are-people-ticklish.

Simpson, Marion. “Why can't you tickle yourself?.” Western Journal of Medicine. June 2001. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1071435/.

“The tickle, a scientific approach behind what it is and why it is needed.” Humanitas Health. March 29, 2019. https://www.humanitas.net/health/health/wellness/3669-the-tickle-a-scientific-approach-behind-what-it-is-and-why-it-is-needed/.

Wattendorf, Elise, Birgit Westermann, et al. “Laughter is in the air: involvement of key nodes of the emotional motor system in the anticipation of tickling.” Social Cognitive and Affective Neuroscience. 2019 https://doi.org/10.1093/scan/nsz056.

Weiss, Suzannah. “This Is Why Some People Hate Being Tickled.” Vice. May 17, 2018. https://www.vice.com/en/article/this-is-why-some-people-hate-being-tickled/.

Westermann, Birgit, et al. “When laughter arrests speech: fMRI-based evidence.” Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences . 2022. doi:10.1098/rstb.2021.0182.

“Why Are People Ticklish?” Cleveland Clinic. Mat 30, 2024. https://health.clevelandclinic.org/why-are-people-ticklish.