There's a difference between being alone and feeling lonely. When we're alone, we consciously choose to isolate ourselves from the crowd, but we can feel lonely even when we're surrounded by family and friends. Some people feel a permanent sense of loneliness, and this may be influenced by factors outside of our social sphere, including our genetics, according to researchers at University of California San Diego School of Medicine.

The degree of loneliness that any two people feel in the same situation may vary widely.

"For two people with the same number of close friends and family, one might see their social structure as adequate while the other doesn't," said Abraham Palmer, lead author of the study, a professor of psychiatry, and vice chair for basic research at UC San Diego School of Medicine, in a statement.

This means some of us have a “genetic predisposition to loneliness.” Genetically speaking, Palmer and his colleagues sought to unveil what makes one person more likely than another to feel lonely, even in the same situation. Palmer and his colleagues found loneliness appears to be a "modestly heritable" trait that’s 14 to 27 percent genetic, compared to previous estimates of 37 to 55 percent. This is lower than previous estimates because the researchers used chip heritability, a method that only captures common genetic variations and not rare genetic variations.

In the study, published in the journal Neuropsychopharmacology, the researchers drew data from the Health and Retirement Study, a longitudinal study of health, retirement, and aging, from which they gathered genetic information for over 10,700 Americans aged 50 and older. Participants answered three well-established questions that measure loneliness; the survey never actually used the word "lonely" since people are reluctant to feel that way.

Instead, the questions asked: How often do you feel that you lack companionship? How often do you feel left out? How often do you feel isolated from others?

The findings revealed strong genetic correlations between loneliness, neuroticism, and a scale of “depressive symptoms.”

Similarly, a 2008 study found loneliness is half inherited and half environmental. Researchers believe part of the explanation for loneliness is evolutionary. Humans would not survive in the wild alone, so they feel a negative signal when they are disconnected from others. There’s also an evolutionary biological explanation to the variation of loneliness. For example, if everyone had a high threshold to loneliness, no one would go out and explore, and vice versa.

"The gene pool is really protected best by variability along that dimension," John Cacioppo, author of the study and director of the University of Chicago's Center for Cognitive and Social Neuroscience, told CNN.

Currently, Palmer and his colleagues are now working to find a genetic predictor or the specific genetic variations responsible for the hereditary trait of loneliness. This discovery could provide additional insight into the molecular mechanisms that influence feeling of loneliness.

Whether we’re genetically predisposed to loneliness or not, we can control it. To cope, a lonely person should acknowledge their loneliness, understand its effects on the mind and body, and respond to it by reconnecting socially. Establishing at least one strong bond is all it takes to feel more connected and less alone.

Source: Gao J, Davis LK, Hart AB et al. Genome-Wide Association Study of Loneliness Demonstrates a Role for Common Variation. Neuropsychopharmacology. 2016.