Do you ever find yourself annoyed by tiny sounds or distractions that others don't seem to notice?
Do you quickly pick up on what someone is feeling, or what their intentions are — even if they haven't expressed them out loud?
Do you get totally overwhelmed by a hectic environment or the sheer number of people whose needs you notice? And do you often need to go somewhere quiet and alone to recover?
If so, you may have been told all your life that you're "too sensitive" and need to "toughen up." But you may not know that this is a normal, healthy trait — and it comes with a distinct evolutionary advantage. If the experiences above describe you to a T, there's a good chance you're a highly sensitive person (HSP).
And, if so, recent research suggests that there's a good reason you sometimes feel overwhelmed.
Although high sensitivity is genetic, there's not just a single gene that causes it. In fact, scientists have increasingly found that personality traits are based on a whole collection of genes, not just one or two. That's true of traits as different as introversion and intelligence.
With high sensitivity, there are at least three separate sets of genes that may play a role — and different highly sensitive people may have some or all of them. Interestingly, every single one of these genes affects your brain or nervous system.
Below, we'll look at each of the three sets of genes. But remember: your genes alone are only part of who you are, and every HSP has grown up with different experiences. Your mileage may vary.
1. The "Sensitive" Gene (Serotonin Transporter)
Serotonin is a chemical in the body that does, well, a lot of things. But one of the most important? It stabilizes your mood.
Serotonin transporter, on the other hand, is a chemical that helps move serotonin out of the brain. So it's the on/off switch for all that mood-balancing serotonin.
And guess what? Highly sensitive people have a special variation of the serotonin transporter gene that behaves a little differently. If you have this gene variant, you have lower serotonin levels, and chances are good you'll be a highly sensitive person. (The gene is officially called 5-HTTLPR, so I'm going to stick with "the sensitive gene.")
This gene variant was originally believed to cause depression, but that's not exactly right. In fact, it doesn't cause any mood disorder at all on its own, but it does make you sensitive to your surroundings — and more likely to learn lessons from them. That matters a lot in childhood development. If you combine this gene with an unhealthy childhood environment, research finds, you have a higher risk of depression and other disorders throughout life. But combine it with a safe, supportive environment, and you get better-than-normal outcomes as an adult. Basically, it may boost the effects of both good and bad upbringings.
So what does this mean if you're a highly sensitive person? Well, you should know that your childhood experiences will have an outsized impact on your wellbeing as an adult. That doesn't mean you can't address and get past the effects of a rough childhood, but it does mean it may affect you more than it might affect others.
2. The Dopamine Genes
While the first gene matters, it's not the only one. Researchers have also found a connection between sensitivity and a set of 10 different gene variants related to dopamine. Dopamine is the brain's "reward" chemical.
Strictly speaking, we don't yet know how these dopamine genes relate to sensitivity, but we have some hints. For starters, it makes sense that someone with a sensitive system would need to feel less "rewarded" by external stimuli — otherwise, you'd be constantly drawn to the same loud, busy environments that exhaust you. (And the evidence bears that out: the gene variants with the biggest effect on sensitivity all have to do with dopamine receptors, which affect how sensitive you are to dopamine in the first place.)
It would also make sense for sensitive people to feel more rewarded by positive social or emotional cues, which they are more tuned into than others in the first place.
As a highly sensitive person, have you ever been baffled why your friends want to go somewhere loud and crazy — or why they'd enjoy a fast-paced, aggressive game? If so, perhaps it's because you don't get the same "dopamine hit" from these loud external stimuli. And that may be some or all of these gene variants at work.
3. The "Emotional Vividness" Gene
Everyone tends to experience life more vividly during emotionally charged moments. But this emotional "vividness" is stronger for some people than it is for others. And it's no surprise that high sensitivity has been linked to the gene variant that controls it.
This gene, which I'll call the "emotional vividness" gene, is related to norepinephrine. Norepinephrine is a neurotransmitter that also helps with the body's stress response. And there's one variant — which may be common in HSPs — that turns up the dial on emotional vividness. If you have it, you may perceive the emotional aspects of the world more vividly. You may also have more activity in the parts of the brain that create internal emotional responses to your experiences.
Most highly sensitive people are keenly aware that they have stronger emotional reactions than the people around them, and often notice emotional undercurrents where others pick up nothing. If you're highly sensitive, this is not your imagination — you may actually have a brighter palette of emotional "colors," so to speak, because of this gene variant. And it directly drives the level of empathy and awareness you have for others' feelings.
An Evolutionary Advantage
Only about 15-20 percent of the population is believed to be highly sensitive. That's uncommon enough that HSPs feel "different" growing up (and are often still misunderstood as adults) but it's a very large number of people. And high sensitivity isn't limited to humans, either; the same trait has been found in at least 100 other species.
Biologists believe there's a good reason for that: being highly sensitive can be an evolutionary advantage. In fact, sensitive people (and animals!) are able to pick up on more environmental cues, recognize things that others don't, and make smart decisions in seemingly new or unusual situations. In many cases, that's a much wiser approach than simply using a set of routines, or charging ahead at random — both strategies that less sensitive animals (and people) tend to use.
This has even been tested out in computer simulations. The simulations showed that individuals who took the time to notice all of the environmental cues before making a decision generally came out ahead — even with a high cost to doing so (in the real world, we call that cost overstimulation). Their sensitivity allowed them to make better and better decisions over time.
But there was a catch: being sensitive was only a benefit if it was in the minority. If everyone is sensitive, we all notice the same details and it no longer gives anyone a special advantage. That's probably why HSPs are relatively rare at about 20 percent of the population and not, say, 80 percent.
So if you've ever found yourself wondering why no one else in your office stops to think things through the way you do, it might actually be a good thing. You have the ability to see things others don't, and that makes you especially valuable.
This post also appeared on Highly Sensitive Refuge, my community and blog for HSPs.