The term "do-it-all-dad" just took on a whole new meaning: Cornell University researchers have recently determined that, in equids at least, it’s the father’s genes that take the lead in developing the mare’s placenta.

“We discovered more paternally (than maternally) expressed imprinted genes in the equid placenta, suggesting a greater contribution of placental development from the paternal genome,” said Xu Wang, PhD, research associate in the Department of Molecular Biology and Genetics at Cornell University, in Ithaca, N.Y. “And this runs counter to your first guess that the female ought to be the one controlling the placenta in her own body.”

But there are complex evolutionary advantages to this design, Wang explained, such as better management of genetic conflict between a male fetus and its mother. And from a breeding point of view, it could help explain the “maternal grandsire” phenomenon—the fact that high-performance foals often skip a generation, coming from the daughter of a champion sire.

While the majority of an organism’s expressed genes come from both the mother and the father, a small number of genes are what scientists call “imprinted,” meaning they are expressed only from the mother or from the father. Technically speaking, this means that one parental copy (the mother’s or the father’s) of that gene is “silenced”–it’s there, but it isn’t expressed