Adult sex friend
Adult friends are, on average, more genetically similar than random pairs from the population (13).Genetic similarity among friendship networks is important for at least two reasons.Using the KING algorithm (25), we computed genetic kinships between all pairs of Add Health participants.We then compared kinships among friends to kinships among random pairs of individuals to estimate the degree of genetic similarity among friends (3).
Our second analysis tested whether friends were more similar to one another on specific phenotype-related genetic dimensions.
Adolescence is a critical developmental period in which patterns of health behaviors and overall mental health established during this phase continue through the life course (16) and may affect socioeconomic attainment (17, 18).
Moreover, it is also a time of heightened salience for peer networks and influence (19–22).
We considered the genetics of three phenotypes: height, body mass index (BMI) (a measure of adiposity), and educational attainment.
We used polygenic scores to summarize phenotype-related genetics.