It is not just the way your partner gazes into your eyes. Your genes may have a major influence in your romantic relationships.
Attraction is a baffling concept, but some clues have been found on the molecular level that could explain the complexity of love.
Humans’ drive to find compatible mates may depend largely on their genetic encoding.
Studies of the major histocompatibility complex genes, which play a major role in immune systems, show that our genes influence our decisions to mate. Even our different personal preferences, personalities and brain systems impact our romantic relationships, UCLA researchers have said.
Nonetheless, science may never fully explain how and why people experience the magic of love.
Elizabeth Pillsworth, a post-doctoral researcher at UCLA who works with the Center for the Study of Women, is currently researching human mating strategies. She investigates people’s idiosyncratic preferences, which, from an evolutionary perspective, have become encoded in genes over time.
She explained that several studies suggest women and men tend to prefer the scent of individuals who are more MHC-dissimilar from them. As a result, MHC genes may help us choose our romantic partners.
MHC genes are involved in immune functioning and have a large variance in alleles. Mating with people who have dissimilar MHC genes from our own broadens the genetic diversity of future generations and therefore makes it more difficult for diseases to overwhelm the immune system.
“There seems to be a strong relationship between having highly variable alleles in this suite of genes and having better immune functioning, because basically, the more variable your alleles are, the more flexible your immune system is to responding to different pathogens,” Pillsworth said.
Peter Nonacs, professor of ecology and evolutionary biology at UCLA, studies the social attraction of some insects.
Nonacs said that insects are oftentimes attracted to each other with the release of pheromones, which are chemical signals.
In humans, however, signals are not nearly as obvious as in insects.
“There’s some kind of odor being given off that we’re not consciously aware of; but subconsciously, things are happening in your body,” Nonacs said.
“What you want in your offspring is to have kids to have as diverse an immune system as you can,” he said.
Other current studies of MHC dissimilarities evaluate people who experience limerence.
Pillsworth described limerence as the “quasi-obsessional feeling of passionate love” at the beginning of relationships.
She is currently investigating whether or not the experience of limerence at the beginning of relationships is directly related to MHC dissimilarities. Limerence has been well-documented, but what triggers the emotion is unknown.
Additional lab studies have shown that men tend to prefer the scent of women who are fertile in the conceptive stage, or the ovulatory state, of their menstrual cycles, Pillsworth said. She explained that preliminary studies are continuing to look at how men differ in their discrimination between fertile and non-fertile women, the strength of their preferences and their innate differences.
There are also significant studies examining sexual development. Eric Vilain, professor of urology and human genetics at UCLA, investigates which genes influence the development of sexual behavior, including individuals’ sexual orientation and behavioral differences between the sexes.
“There is less clear evidence that it’s only genetic. There are a combination of genetic factors, a lot of factors ““ probably environmental factors, in which all contribute to the sexual development of the brain and the behavior,” he said.
Despite the multitudes of studies on romantic relationships and sexual behavior, researchers are far from finally solving the mystery of love.
“We are only just beginning to look at some of the biological mechanisms that draw you to one person rather than another,” said Helen Fisher, a research professor in the department of anthropology at Rutgers University.
Fisher explained that there are biological and psycho-social reasons that explain why we fall in love with one person rather than another.
Psychologists know that these reasons show people tend to fall in love with others with the same socioeconomic background, ethnic background, general level of intelligence, general level of good looks, educational level, and religious and social values, she continued.
“We tend to fall in love with somebody who can give us what we need in exchange of giving them what they need. You tend to fall in love with somebody who is in love with you ““ that’s very attractive,” Fisher added.
In her new book, “Why Him? Why Her?” Fisher identifies four biological personality styles, which are generated by brain chemistry.
She believes we are attracted to people with certain traits of temperament we find desirable. Humans, she said, have two parts to their personality.
“There’s your character, which is everything you grew up to believe and do and think and say, and then your temperament, which is all the traits that evolved, that you have inherited.”
She said that there are three major systems for mating and reproduction, which are sex drive, romantic love and deep sense of attachment. These brain systems are linked with hormones like oxytocin and vasopressin and neurotransmitters like dopamine.
The extent to which science can fill in the holes to understanding love’s mysteries is debatable. Science may or may not fully unravel the intricacy of love in the future.
Pillsworth explained that love is a wonderful feeling, and it will always be an experience.
“Even if we understand some of the underlying mechanisms of what triggers turning us on or turning us off, the experience (of love), the way it feels (between) people, it’s automatic,” she said. “Some people, I think, express concern that science will take the romance, mystery or fun out of love. I don’t think it can do that.”
While science cannot tell us who to fall in love with, Pillsworth said, “It can … potentially help us answer some questions about pressures in the relationship and some of the difficulties that people have.”
It goes without saying that our romantic partners’ names are never going to be written on our genes.
“Human behavior is always going to be affected by genes, but they don’t determine really who we are,” Nonacs said. “It’ll have an effect, but you can’t go and look at your genotype and know who you’re going to marry.”
Fisher is certain that “it will always be magic to love,” she said. The complexity of the brain and our bodies assists people when they choose their mates, but love will eternally remain a puzzle for scientists and lovers alike. Fisher said, “The brain is a beautiful mechanism for weeding between our sea of mating opportunities and choosing certain individuals. And we’ll never know all of it. Never.”