Marital behaviours are important human traits of great interest in sociology, psychology, and related fields. Sociological factors (e.g. educational attainment) have been demonstrated to strongly associate with AFM, especially for women. However, little is known about the genetic basis of marriage. Due to the growing interest in understanding the genetic basis of marriage and how it interacts with environmental factors, this proposed research will study the sociological factors associated with people’s age at first marriage (AFM) using a genetic approach. More specifically, this research aims to identify common genetic variants associated with AFM through a genome-wide association meta-analysis approach. In addition, we will quantify the genetic correlation between AFM and a variety of human traits such as personality and cognitive behaviour, assess the predictive accuracy of AFM using genetic information, and investigate how genetic and environmental factors interact to influence AFM. This research will potentially provide fundamental new insights into the genetic basis of marital behaviour in general and AFM in particular.