Behavioral-genetic associations in the Human Connectome Project

The Human Connectome Project (HCP) provides a rich dataset of quantitative and domain-specific behavioral measures from twins and extensive family structures. This makes the dataset a unique and a valuable resource to investigate heritability and determine individual differences. Using a set of measures of behavioral domains (motor, emotion, personality, sensory, and cognition), we estimated the intraclass correlations (ICCs) and heritability of 56 behavioral measures for 4 genetically identified groups of participants: monozygotic (MZ) twins, dizygotic (DZ) twins, non-twin siblings (SB), and unrelated individuals (NR). The ICCs range varied among behavioral domains but systematically so among the four genetic groups. We found the same rank order of ICCs, from the highest values for MZ twins, statistically significantly smaller for the DZ twins and sibling group (compared to MZ), and close to zero for NR. The mean heritability values of the five behavioral domains were: cognition h2 = 0.405, emotion h2 = 0.316, motor h2 = 0.138, personality h2 = 0.444, and sensory h2 = 0.193. These domains share overlapping brain networks. The heritability of motor domain was significantly smaller than cognitive, personality, and emotion domains. These findings provide new insight into the effect of genetics on the various diverse behavioral measures.