'I thought I knew how to date. Then I learnt about the "alien theory."'

I don't know if I believe in soulmates. I mean, I certainly haven't found mine yet. But, perhaps I've been going about it all wrong.

You see, I usually date people who look nothing like me. This, according to the old wise one (AKA TikTok) is a big no-no if I want to meet my twin flame… soul-tied connection… one true love… whatever you want to call it.

Yep, according to manifestation coach Nadia Khaled, in order for someone to be your true soulmate, they have to look (at least a little bit) like you.

Ermmm, it's giving that scene in White Lotus, but let's hear her out.

Watch: The number one cheating sign that everyone misses. Post continues after video.

"I can always tell when two people are soul mates versus when they're just not really meant to be together," Nadia shared on TikTok.

"It's one thing that I look for, and it has been consistent in every single happy, healthy, long-term relationship I've ever seen. They all have this: and it's that they literally look physically similar to each other."

She went on to say that these similarities are "not always super obvious", and it can be as small as one minor detail.

On the opposite end of the spectrum, Nadia claimed that couples that don't look anything alike are "not meant to be together" or, at least, are not "soulmates".

Here's where the alien part comes in:

"The best way I can explain it is, if all of us were aliens that all came from different planets, soulmates would be two aliens from the same planet. So they look kind of similar. But if they're not soulmates, they look like they both came from two completely different planets, like two completely separate types of aliens.

"Call me crazy, but now that I pointed it out, you are going to start to notice it all the time."

At first, I thought this "alien" theory was just a bit of fun and whimsy! A silly, goofy idea that didn't hold any real weight in relationships.

That was until I spoke to a psychologist about it…

As it turns out, there is actually some science behind the "alien" theory. Though it's actually called 'assortative mating' (boooooring).

Basically, assortative mating is where individuals choose partners based on similarities in certain traits, even without being explicitly aware they're doing it.

According to clinical psychologist Dr Katie Kjelsaas, overseas research shows spouses are, on average, more genetically similar than two randomly chosen individuals. And there are a number of theories for why this is the case.

"The ones that make the most sense to me, as a relationship therapist, are the social theories," Dr Kjelsaas told Mamamia.

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"A kind of 'cringe' human example would be a dating app — more 'attractive' people (whatever that means) get more right swipes and the algorithm responds to this, showing their profile more. They're therefore seen by more people, obtain more potential matches and have more choice in potential 'mates', allowing them to be more choosy.

"By contrast, less 'attractive' people get fewer right swipes, get a smaller pool of potential matches to choose from, and can be less choosy. In both examples, people end up with those who are similar in 'attractiveness.'"

There are also some "really cool genetic reasons" for assortative mating.

"In humans, assortative mating seems to work to make people match up on genes where a gene match makes their offspring stronger," Dr Kjelsaas said, "but also to not match up on genes where a gene match would make offspring weaker.

"For example, chromosome six — if parents match genes here, their kids are more vulnerable to pathogens, but those same married couples who are more genetically similar than two random individuals tend to be less genetically similar on this chromosome than two random individuals."

And it's not just looks that can be similar.

"From a social standpoint, assortative mating also means people are somewhat more likely to pair up with others similar in socioeconomic status and/or religious or spiritual values," said Dr Kjelsaas.

"It's fairly intuitive why matching on these often-important, values-related characteristics may make it easier for couples to have harmonious and long-lasting relationships."

However, she says, it's important to note that assortative mating can have some negative long-term consequences, including the concentration of generational wealth, and greater division between social groups.

The reaction to Nadia's "alien" theory on TikTok has been mixed, with some jumping on the idea.

"That is why me and my ex didn't work out," suggested one user.

"He looked like a rat and I look like a princess."

Feature Image: Instagram/@nadia.khaledd