The paradigm examples of genes contributing to behavior are studies of [male] homosexual preference among identical twins, where one twin is homosexual.
(genes; contributing; to behavior) (The paradigm examples of genes; are; studies of [male] homosexual preference among identical twins) (one twin; is; homosexual; L:identical twins)
genes The paradigm examples of genes one twin
contributing are is
to behavior
studies of [male] homosexual preference among identical twins
homosexual L:identical twins