Gazing longingly into your partner's eyes is easier to do when you're both standing at about the same height, and according to a new study, there's a good reason for that.

Researchers in the UK have found that the genes that determine how tall we are also influence how people are attracted to partners of similar height to themselves.

Scientists led by the University of Edinburgh analysed the genetic information of more than 13,000 heterosexual couples and found that the factors behind people's mate choices share a huge degree of overlap with the genes responsible for our stature.

"Our genes drive our attraction for partners of similar height to ours, i.e. tall people pair with tall people," said lead researcher Albert Tenesa. "We found that 89 percent of the genetic variation affecting individual preferences for height and one's own height are shared, indicating that there's an innate preference for partners of similar height."

Sourcing their data from the huge UK Biobank study, the team extracted 13,068 White-British male-female couples and analysed the genotype of the 26,136 individuals involved.

According to the researchers, within this subset of data, the genotype of an individual could be used to predict their partners' height with 13 percent accuracy. That might not sound like much, but once certain heritability factors were accounted for, it's actually 64 percent of the theoretical maximum.

"The similarity in height between partners is driven by the observed physical appearance of the partner, specifically their height, rather than influenced by the social or genetic structure of the population we live in," said Tenesa.

"How we choose our partners has important biological implications for human populations. This study brings us closer to understanding the complex nature of sexual attraction and the mechanisms that drive human variation."

However, the study's conclusions – reported in Genome Biology – conflict in part with that of another paper published recently.

A study by researchers from Konkuk University in South Korea found that the greater the height difference between males and females in relationships, the happier the female ended up being – at least for a time, as the influencing effect seemed to wane over many years.

"Nevertheless, the long period of the dissipation indicates a powerful impact of male height on women's psychology, probably prepared by evolution," the author concluded.

Taking these two studies together, it seems that the links between height, attraction, and happiness remain a little unclear, so as far as finding the perfect partner goes, the jury is still out.