Six celebrities you didn't know had a twin.

There was an ad a couple of years ago featuring a rather famous celebrity’s brother.

Remember, Doug Pitt for the Virgin mobile ad?

If you don’t, here’s what he looked like:

People collectively lost their minds to realise that, 1) Brad Pitt had a brother (who we didn't know about) and, 2) Ummm, he awkwardly lives in his brother's shadow.

A friend recently reminded me of said ad earlier this week, which sent me down a dark celebrity sibling rabbit hole.

And, in particular, celebrity twins.

I'm not talking about the popular twins we know about, like Mary-Kate and Ashley Olsen, or Benji and Joel Madden.

I'm talking about the Doug Pitts of the world.

Scarlett and Hunter Johansson

Maybe this one isn't so secret because Hunter is often his sister's right-hand man on red carpets.

Exhibit A:

While Hunter did some acting during the 90s, he eventually continued his career in politics.

Fun fact: he was even part of the original campaign that elected Barack Obama in 2008 and secured his re-election in 2012.

Listen: Anne Stephens talks Sarah Macdonald through raising two sets of twins in two years. Post continues after audio. 

Laverne Cox and M Lamar

Okay, so this is the one that has properly shaken me.

If you have ever watched Orange Is The New Black you may remember the flashback to Cox's character that led to her imprisonment. The flashback depicts Cox as male, prior to her transition, where she stole credit cards to finance various surgeries.

REMEMBER? 

At the time, I honestly thought Cox had some serious make-up applied, or the OITNB casting team had worked darn hard to find her doppelganger.

It didn't even cross my mind that maybe it was her twin.

WHICH IT IS.

A post shared by laverne cox (@lavernecox) on Oct 5, 2017 at 10:51am PDT

His name is M Lamar, who is a New York City-based musician. Mind. Blown.

Ashton and Michael Kutcher

Ashton Kutcher may have won many hearts in That 70s Show, but it was his brother Michael, who hugely influenced him.

Having a heart transplant at 13 and living with cerebral palsy, Ashton says the treatment of Michael showed him the reality of our society.

"My brother was born with cerebral palsy and it taught me that loving people isn't a choice and that people aren't actually all created equal," he said. 

"We're all created incredibly inequal to one another, in our capabilities and what we can do and how we think and what we see. But we all have the equal capacity to love one another."

Michael currently works as a motivational speaker.

Gisele and Patricia Bündchen

Supermodel, Gisele Bündchen, didn't just grow up with a twin sister, Patricia, - but with four other siblings.

Patricia was reportedly born about five minutes before Gisele and occasionally attends some star-studded events with her sister.

Feliz aniversário super Pati! Obrigada por seres minha melhor amiga desde o dia em que nascemos. Te amo com todo meu coração!!! #gratidão #irmãgêmea #família #amor ????????????❤???? Happy birthday super Pati! Thank you for being my best friend since the day we were born. Love you with all of my heart!!! #gratitude #twinsister #family #love

A post shared by Gisele Bündchen (@gisele) on Jul 20, 2017 at 1:59pm PDT

Alanis and Wade Morissette

It's taking every inch of me to not make some terrible, 'Isn't this ironic joke', but it's 2017 and I should be coming up with new material.

I digress.

Alanis' twin brother, Wade Imre, is just minutes older than her, who is a yoga instructor and is also involved in the indie rock music scene.

4 legged bliss

A post shared by WIM (@wadeimremorissette) on Sep 26, 2017 at 7:51pm PDT

In a lovely tribute to her brother, Alanis named her son, Ever Imre.

Cole and Dylan Sprouse

Most Gen Y readers would be rolling their eyes as though this is some 'unknown' celebrity twins when they actually came to fame being twins.

BUT. Many people may only have discovered Cole from watching the recent Netflix hit, Riverdale. 

Prior to landing that role, he starred with his brother, Dylan, on Disney's show, The Suite Life of Zack and Cody. 

Come on, guys: