Many believe romance happens by chance, but finding your loved one may be a bit more predictable than that. New research published in Genome Biology suggests genes that determine people’s height also influence who they want to romance, and provides a deeper understanding of why people tend to have partners of similar heights.

Height is a quantitative trait that is determined by the interplay of several genetic and environmental factors. Although previous studies have found height was a key trait when choosing a significant other, there has been no explanation for why humans find individuals of a similar height attractive. The current study found that the choice of a mate with a similar phenotype is genetically determined.

“Our genes drive our attraction for partners of similar height to ours [i.e. tall people pair with tall people]. 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,” lead author Albert Tenesa said in a statement.

Researchers recruited more than 13,000 heterosexual couples to determine how much attraction to a mate with a similar height could be explained by a person's genetic make-up. Among this group, they found a strong correlation between a person's height and their preference for a partner with similar height — this was supported by both partners having similar genotypes, or genetic makeups.

The investigators then used an independent dataset of 15,437 couples where only one of the partners had been genotyped in order to predict the other partner’s height. "Using one partner's genes for height, we estimated the height of the chosen partner with 13 percent accuracy,” Tenesa said. “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.”

Mate selection driven by height has important social and biological implications for human populations. This mating pattern is known as assortative mating, where people pair up with others on the basis of similar genotype or phenotype more frequently than expected by chance.

“Assortative mating influences how DNA variation is arranged in the genome, which may have important implications for other human traits including disease susceptibility,” the researchers wrote.

These finding provide new insight into the mechanism that influence mate choice and drive human variation.

Source: Tenesa A, Rawlik K, Navarro P, Canela-Xandri O. “Genetic Determination of Height-Mediated Mate Choice. Genome Biology. 2016.