Temporal Stability in Group Favoritism is Mostly Attributable to Genetic Factors

Twin studies of in-group favoritism have reported roughly equal influences ofgenetic and environmental factors. All, however, have solely relied oncross-sectional approaches, leaving open the question of whether genetic... [ view full abstract ]

Twin studies of in-group favoritism have reported roughly equal influences of
genetic and environmental factors. All, however, have solely relied on
cross-sectional approaches, leaving open the question of whether genetic and
environmental factors have similar roles on stability and change for in-group
favoritism across time. While in-group favoritism is commonly perceived to
reflect environmental influences, stable environmental effects are rare for
psychological traits, thus suggesting that genetic influences may play the
majority role in the stability of favoritism. Here we used addressed this issue
using a 10-year (two-wave) longitudinal twin design. In-group favoritism showed
high rank-order stability (r=.67). Seventy four percent of this rank-order
stability was attributable to genes. A broadly similar pattern was observed for
race, ethnic, and religious favoritism. By contrast, changes in favoritism almost
entirely reflected nonshared-environmental influences. These findings indicate
that environmental influences underpin change in favoritism, while the stability
of favoritism mostly reflects genetic influences.