Friends tend to be somewhat closer if their demographic characteristics are similar

Research published in the Journal of Social and Personal Relationships revealed that friends who share similar demographic characteristics, such as age and gender, tend to report higher emotional closeness. This connection was found to be stronger among women than men. The study, authored by Markus Jokela, analyzed data from the PAIRFAM data, a German family panel study initiated in 2008 with 12,000 participants from three birth cohorts.

The analysis included 7,699 participants, with an average age of 26 years, and a majority being native Germans or ethnic German immigrants (84%). Participants listed up to 30 friends and rated their emotional closeness to each of them. The study found that participants rated their friends who were the same age as somewhat more emotionally close, regardless of gender.

Women tended to rate friends of the same sex as closer than male friends, while for men, the sex of the friend did not affect emotional closeness. Parental status was linked to higher closeness for men but lower for women, and marital status showed a weak association with emotional closeness. Additionally, participants with personality traits such as extraversion, agreeableness, conscientiousness, and openness to experience reported higher emotional closeness with their friends.

The study supports the similarity-attraction hypothesis, demonstrating that sociodemographic similarities and personality traits influence friendship and emotional closeness. However, the study cannot establish causation, and results may vary among different ethnic or age groups due to the mostly young German participant base.