(and no, yours isn’t the odd one out)

We all know the phrase “everyone’s different.” Usually it’s muttered when Karen at work hoards the good pens, and someone sighs, “Well… everyone’s different.” But here’s the thing: that’s not just a polite way of saying she’s selfish. It’s literal, chemical scientific fact.

And for all those among us who have trust issues (everyone reading this I’m sure, and that’s okay) there’s even real undeniable empirical evidence brought to you by real actual scientists that spent their life learning about it. And they wouldn’t spend their life learning about something just to lie to you, that would be boring and weird.

Your Brain is A Bartender with No Rules

Inside your skull is a nightclub. Your brain cells (neurons) are the bartenders, and the ingredients they’re using to make your drink are your brain chemicals (neurotransmitters): serotonin, dopamine, norepinephrine, glutamate, GABA.

The problem? Every brain-nightclub makes drinks in totally different ratios, responding to external stimuli but they don’t quite remember what that stimulus was or why it has anything to do with the drink they just made. So:

• Some brains are sipping calm herbal tea.
• Some are knocking back triple espressos at 7am.
• Some ordered a mojito but accidentally got tequila shots, and now they’re crying in the club.

The kicker, no two brain-bars serve the same menu, and you can’t just hop over to someone else’s when you’ve had enough of this one, the bouncers have locked you in for life.

So, what this means in reality is that your brain uses a mix of all of those pesky chemicals I mentioned a few sentences ago, that you totally skipped over, (and are now going back to look at) to create your personality. But what does that even mean?

What is personality?

The word personality gets tossed around like its tabloid fluff. He’s got such a big personality! Yeah, okay, but what does that actually mean? Spoiler: it’s not just whether you like pineapple on pizza.

Personality is the full set of traits, habits, and reactions that make you consistently and reliably you across every situation you will encounter in your life. That consistency is what allows those closest to you to confidently say ‘you don’t seem yourself, what’s wrong?’ when you think you’re hiding something really well.

And science always brings receipts:

1. Temperament (your factory settings)
   

This is your starter pack. Babies are born wired differently: some arrive snoozing peacefully, others arrive screaming like they’ve just seen a 2025 electricity bill. That built-in emotional tone is mostly down to genetics and early brain chemistry, and it sets the groundwork of who you will eventually become, after you start consciously experiencing the world.

2. Traits (the Big Five, and no, we aren’t talking accountancy)

Psychologists tell me that they measure personality in five big categories, very creatively called the Big Five (I just saw the corporately traumatised among us flinch, for the second time in 2 sentences):

• Extraversion: Do you recharge by going to a rave or by binge-watching alone in bed?
• Openness: “Let’s go backpacking through Mongolia” vs “let’s go to the same pub forever.”
• Conscientiousness: Meticulously organized, or living in what archaeologists will one day call a mess.
• Agreeableness: Do you naturally say yes or is your aura pure don’t test me.
• Neuroticism: Rock-solid calm, or one stubbed toe away from a full breakdown.

Fun fact: these traits are surprisingly unbudgeable. You can nudge them with therapy, habits, or trauma, but you won’t wake up one day with a whole new personality.

3. Habits (the messy middle)

This is the layer that feels the most you. Whether you’re chronically late, have a color-coded wardrobe, or eat crisps like you’re training for the Olympics, these repeated behaviours become signature parts of your personality.

4. Emotional style (your brain’s own instruction manual)

This is your brains comprehensive instruction manual on how your nervous system should respond to life. And you guessed it; everyone’s instruction manual is different. For example, two people can sit right next to each other and watch The Lion King:

• Person A cries like Mufasa were their actual dad.
• Person B scoffs popcorn and mutters, “Circle of life, babes.”

Neither is wrong. Their brains are just built differently, often through neurotransmitters (chemical messengers your brain cells use to text each other instructions like “be happy,” “panic now,” or “eat the whole packet of crisps”).

These neurotransmitters are those words you heard that TikTok psychiatrist throw around like serotonin (mood stability), and norepinephrine (fight-or-flight alertness).

5. Social patterns (how you do human-ing)

Are you a group-chat enthusiast, or do you ghost after three texts? Do you make ten new friends on holiday, or do you hide behind a book until it’s time to go home? That’s personality too, chemically rooted in your hardwiring, and as much as some people do some questionable things, it’s not exactly a “choice.”

So, What Does That Really Mean?

Personality is basically your operating system, just like that MacOS update you’ve been hitting remind me later on for months. It’s not just your “vibes.” It’s your brain’s long-term complex mix of chemicals (serotonin/dopamine soup), structure (how your neurons are wired), and experience (that life nonsense that constantly tweaks the recipe).

Dear diary, WTF: personality isn’t some woo-woo aura. It’s science deciding whether you’re coded as golden retriever, cautious tortoise, or feral raccoon with a bin lid.

So, how do these mysterious brain chemicals control you?

• Mood: Low serotonin? Life feels like a shitty Monday. High serotonin? Even pigeons look majestic.
• Focus: Some people can finish a 400-page novel in one night. Others can’t finish a writing a text before they’ve opened TikTok and started scrolling. That’s dopamine deciding whether your brain thinks this is interesting I’ll keep engaging with it or nah, time to scroll.
• Stress: One person hears thunder and thinks “cozy.” Another hears it and thinks “apocalypse.” That’s norepinephrine, the brain’s alarm bell, deciding whether to whisper relax or scream RUN.

The Cocktail Problem

Scientists sometimes pretend they can measure all of this neatly, but your brain is basically a cocktail with no recipe. A spicy, sweet, messy, chaotic, and ever-changing cocktail.

Think about it, even identical twins (exactly the same genes, same womb, same childhood home) end up with slightly different cocktail recipes, and completely different personalities because of it. One gets extra salt; the other gets an accidental chilli pepper.

That’s why one person can take an antidepressant and suddenly feel like Beyoncé, while another just gets sweaty. It’s not willpower, it’s about whether your cocktail accepts the new ingredient or spits it out.

“It’s Their First Time on Earth Too”

You’ve probably seen that new cliché floating around Instagram: “Be kind, it’s their first time on Earth too” At first glance it sounds like something you’d see printed on a mug next to a plant you forgot to water. But buried under the cute font and carefully selected background colour is a genuinely useful truth.

If everyone’s brain is a custom cocktail, then everyone is also dealing with their own unpredictable mix of overwhelming emotions. That person who panics about a wasp? Their norepinephrine just went DEFCON 1. The mate who gets weirdly furious when the Wi-Fi lags? That’s dopamine withdrawal playing dirty tricks. The friend who cries when their sandwich falls on the floor? That serotonin dip is real.

And here’s the part no one can fully trust: it’s not like everyone else got some kind of “brain cocktail override” while you’re the only one left stuck with emotions you don’t really want or understand. Nobody got a manual. Nobody got a cheat code. We’re all first-timers here, armed with nothing but badly wired chemistry sets, ChatGPT, and pure vibes.

Trusting that reality can make it a tiny bit easier to give yourself and other people grace, because no one’s emotions are as rational or controllable as they may look from the outside.

Myth-Busting: Personality Edition

• Myth 1: Personality is fixed forever.
  It’s stubborn but not set in stone. Big life events, therapy, or even just aging can shift things slightly. Think of it like your drink order changing from vodka shots at 18 to oat flat whites at 30.
• Myth 2: Mood = Personality.
  Mood is temporary day to day weather, personality is climate. Rainy Tuesday doesn’t mean you live in the Arctic.
• Myth 3: Willpower fixes everything.
  Your cocktail (brain chemistry) sets the stage. Willpower helps you work with what you’ve got, but it doesn’t rewrite the recipe. You can’t positive think yourself into different brain chemicals.
• Myth 4: Anyone else is experiencing the same reality as you.
  Absolutely not. That’s the whole point of this blog. Your bestie might genuinelylove running marathons while you’d rather fake an injury than jog for a bus. Different cocktails, different outcomes, lots of ‘I don’t know how you can do that for fun’.

So, when someone says, “everyone’s different,” don’t just roll your eyes. They’re factually correct, after all. Your brain is running on a cocktail that is completely exclusive to you. There’s no menu, no tradesies with the girls, and definitely no remakes.

Some of us got fancy martinis. Some of us got a WKD Blue with a paper straw. Some of us got a drink that looks suspiciously like pond water but somehow keeps us alive. It isn’t fair and it isn’t based on merit, but it is how it is.

Cheers to surviving your one-of-a-kind, chaotic, chemically questionable brain.

Why This Isn’t Just Woo

The whole “everyone’s different” line actually isn’t just some Pinterest quote. It’s backed by decades of neuroscience, personality psychology, and studies of genetically identical twins. Your personality isn’t a choice that you can just change overnight, it’s biology plus chemistry plus time plus life experiences, shaken (not stirred).

Receipts (for the girlies questioning their brain cocktails)

• Robert Sapolsky – Behave: The Biology of Humans at Our Best and Worst A doorstop-sized but brilliant look at why your neurons sometimes act feral and sometimes saintly. Every “WTF is wrong with me” moment explained, minus the shame.
• Daniel Nettle – Personality: What Makes You the Way You Are The most readable deep dive into the Big Five traits without turning your brain into a spreadsheet.
• David J. Linden – The Compass of Pleasure Explains how the same brain circuits drive love, drugs, food, and your obsession with checking if they’ve viewed your story.
• Robert Plomin – Blueprint: How DNA Makes Us Who We Are Not destiny, but data. How your genetic code quietly sets the stage for every bad decision you think was “just vibes.”
• Lisa Feldman Barrett – Seven and a Half Lessons About the Brain Short, smart, and surprisingly funny. Perfect for when your attention span is running purely on dopamine fumes.
• Daniel Kahneman – Thinking, Fast and Slow For when you want to understand why your brain makes dumb snap judgments and then writes a 600-word essay defending them.
• Judith Rich Harris – The Nurture Assumption The controversial one that says parents don’t make you — peers do. Good to read if you’ve already sent your therapist a small novel about your mum.
• Jerome Kagan – The Temperamental Thread The scientist who proved babies come pre-installed with their own personalities. A gentle reminder you weren’t “dramatic as a child,” you were chemically distinct.
• Oliver Sacks – The Man Who Mistook His Wife for a Hat Classic neuroscience storytelling that turns brain quirks into empathy lessons. Bonus: makes you feel normal for once.
• Kay Redfield Jamison – An Unquiet Mind A psychologist with bipolar disorder breaks down mood chemistry with painful honesty and black humour. Proof the brain’s cocktail menu can be both beautiful and brutal.

Bonus Articles & Essays

• “The Big Five Personality Traits: A Scientific Breakdown” — APA.org
• “The Neuroscience of Personality: How Brain Chemistry Shapes You” — Scientific American
• “Genes, Temperament, and the Twin Studies Revolution” — Nature Reviews Neuroscience
• “Serotonin Isn’t Simple: What Science Actually Knows About Mood” — The Guardian Science Weekly