Genetics are at least partly to blame for life-long loneliness, according to the largest ever study of the personality trait’s heritability.
American researchers found that the tendency to feel left out, isolated and lacking companionship over a lifetime is between 14-27% genetic.
Scientists described the trait as “mildly heritable”, but said environmental factors were still more likely to be responsible for a recurring sense of isolation.
The researchers also found that people who inherit loneliness tend to inherit neuroticism - a long-term negative emotional state.
In a statement, a spokesperson added:
“Weaker evidence suggested links between heritable loneliness and schizophrenia, bipolar disorder and major depressive disorder.”
Loneliness has previously been linked to poor physical and mental health, and is thought to be as big a killer as obesity.
Abraham Palmer, professor of psychiatry and vice chair for basic research at UC San Diego School of Medicine, said:
“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.
“And that’s what we mean by ‘genetic predisposition to loneliness’ — we want to know why, genetically speaking, one person is more likely than another to feel lonely, even in the same situation.”
In two previous, smaller studies, scientists found that genetics played a bigger part in loneliness. Previous estimates suggested 37 to 55%.
The lower figure could be explained by the fact their study focused on chip heritability, a method which excludes rare genetic variations.
Previous studies found that loneliness was associated with variations in specific candidate genes, including those which encode dopamine.
But the latest study didn’t find that any single gene could be responsible.
These results could differ because the team studied older adults in the US, whereas previous research focused on younger Europeans, researchers said.
They are now attempting to pinpoint a specific genetic variation responsible for loneliness.
The team analysed genetic and health information from 10,760 people aged 50 years and older.
The study was published in Neuropsychopharmacology.