A recent study investigated the role of genetics in how we experience loneliness, social isolation and depression. The researchers used data from a longitudinal twin study that has been collecting data on 1116 pairs of same-sex twins born in the U.K. in 1994 and 1995.
Social isolation refers to an objective state in which we have limited social connections and interactions. Loneliness, on the other hand, is an entirely subjective state, in which we feel socially and/or emotionally disconnected from those around us. As such, socially isolated people are not necessarily lonely, and lonely people are not necessarily socially isolated.
Loneliness has been found to be a much bigger risk factor for depression than social isolation. Indeed, the researchers found that lonely people were much more likely to report symptoms of depression than people who were social isolated.
Loneliness tends to create distorted perceptions and pessimistic mindsets that can lead to depression. Being lonely makes us judge our friendships and relationships more negatively and respond to others more defensively and even with greater hostility—which can push people away and sabotage opportunities for closeness and meaningful interaction. Thus, these behaviors can set us up for being both more socially isolated and more depressed.
Here’s where the genetics come in. These kinds of negative response sets can be inherited. If we have such genetic predispositions, our 'default' reactions might be setting us to respond to feelings of loneliness in ways that are likely to actually increase our social isolation and our depression.
Researchers confirmed these assumptions. The data showed significant indications of genetic correlations between loneliness, social isolation, and depression. They concluded that while not all people who are socially isolated are lonely, those who do experience loneliness are often depressed as well because of this similar genetic influence.
While a specific ‘loneliness gene’ has not been isolated (and might never be, as loneliness might result from a confluence of several genes rather than just one), the findings do reinforce those of other studies that have also found genetic predispositions to loneliness.
The good news is that regardless of whether we are genetically predisposed to loneliness, the power to extract ourselves from its clutches remains in our hands (read "Why Loneliness Is a Trap and How to Break Free"): Doing so involves correcting our negative perceptions of our relationships (by assuming people care for us more than we believe they do and giving them the benefit of the doubt), taking active steps to reach out and connect with others (however emotionally risky it feels to do so), and monitoring our reactions to limit defensiveness and hostility and make efforts to come across more warmly and openly (even if it feels unwise and unsafe to do so).
Matthews, T., Danese, A., Wertz, J. et al. Soc Psychiatry Psychiatr Epidemiol (2016) 51: 339. doi:10.1007/s00127-016-1178-7
Goossens, L., van Roekel, E., et al. Perspect Psychol Sci. 2015 Mar;10(2):213-26. doi: 10.1177/1745691614564878.