Hint: It's all in the genes.

You may or may not remember the fateful moment you met your significant other — aka ‘the one.’ If you do, you might think it was their smile, their eyes, or some unfortunate chat-up line that caught your attention. But, according to a study by Nature, there's a scientific reason for why sparks flew.

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The data finds that everyone has a unique human leukocyte antigen (HLA) complex that primarily helps distinguish between native cells and icky viruses and bacteria. In addition, the HLA complex can be a key factor in determining chemistry and attraction with others.

Researchers looked at the attraction pattern of 254 couples and determined that having different HLA complexes ‘correlates with sexuality and enhances the desire to procreate’ for those couples.

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Findings also suggest that the reason someone thinks their partner smells so good has to do with differing levels of HLA complexes, too. But, in the end, the people studied were already in a relationship so their bias could be the reason for that.

So the next time you're at the bar, just ask the hottie you've been eyeing all night what his or her HLA blueprint looks like and compare with yours before you start planning your future together.

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Article courtesy of Carson Blackwelder at InStyle.com