> Theoretically mitochondrial DNA (which is maternal-only) could do the trick. That is, sperm have just one mitochondrion, and they almost always dump it as pa

> Theoretically mitochondrial DNA (which is maternal-only) could do the trick. That is, sperm have just one mitochondrion, and they almost always dump it as part of fertilization. But not always, so there is nonzero male contribution of mitochondrial genes.