The widespread popularity of apps like Tinder has propelled online dating into the mainstream. Meeting people via the internet is now the norm and the shamefaced days of secret profiles are largely gone.

Yet, doubts remain about whether it’s possible to judge a potential partner’s compatibility through these services. OK, you might be able tell if they’re aesthetically pleasing from their photos, while their hobbies might suggest a shared love of cycling, but how do you know if there's chemistry? A startup named SingldOut, which contacted me with news of its $500K seed round, claims to have a scientific answer to this problem.


DNA Compatibility

Like other dating platforms, SingldOut charges users a membership fee (ranging from USD $65-25 per month) to find and make contact with potential matches. However, while might connect users because of similar interests, SingldOut looks for “biological compatibility”. Each user has a genetic profile saved on the site which can be compared to those of other members.

This genetic data is gathered from each user when he or she signs up to the platform. DNA testing kits, provided by a partner company named Instant Chemistry, are sent out to members. The members return the kits with saliva samples which are then analyzed in the lab.

We’re not talking full genetic profiling here. Instead, the company is focused on two sets of genes - the serotonin transporter gene and the human leukocyte antigens - which it says determine compatibility.

When testing is complete, the results appear in the user’s login on SingldOut, ready for chemistry comparisons. Users will also have filled out psychological questionnaires and received a personality report in return which is also used for match-making.


The science of attraction

It all sounds a bit pseudo-scientific but SingldOut and its Canadian partner Instant Chemistry claim that the genes analyzed via its testing service directly impact compatibility and relationship satisfaction.

It’s true that serotonin is believed to affect a person’s mood and social behavior. The serotonin transporter carries the chemical into the nerve cells and there is evidence to suggest that variation in the encoding gene impacts how a person responds to situations. For example, research suggests that some variants affect a person's ability to handle stress. Other psychological reports have demonstrated low marital satisfaction in couples where an individual has two short alleles of that gene and have been exposed to more negative and fewer positive experiences in the relationship. It’s possible therefore that testing for this gene variant could reduce the dissatisfaction risk.

The data around the human leukocyte antigens (HLA), which regulate a large part of the immune system, is conflicting. The theory is that individuals are attracted to those with different immune systems to their own, perhaps with the aim of producing stronger offspring.

However, while there is research to support the idea that humans are attracted to dissimilar HLA haplotypes (i.e. inherited genes), the story is very mixed. Indeed other reports suggest greater attraction to people with similar HLA haplotypes.

Of course, being told that you have a genetic match or clash with another person is a powerful attractant or repellent in itself, at least in the short-term. It’s easy to convince yourself that something is biological, that it’s meant to be. But in summary, the science of attraction is complicated and probably too erudite a subject for today’s tests to provide any certainty.

Nevertheless, as sequencing becomes cheaper and more information about us as individuals becomes public, choosing partners according to their genetic strengths doesn’t seem too much of a stretch.