More than 80 percent of the mouse genes had variations in the nearby regulatory DNA that affects gene activity. Genes are inherited in pairs, or alleles, with one allele from each parent. Expression in 95 genes in the brain depended more on being inherited from one parent than the other. For thousands of genes in the brain, there is a slightly greater expression of genes inherited from the father than from the mother.
Credit: Ernesto del Aguila III, NHGRI.