I know fiction about extraterrestrials is not directly applicable to this argument, but I feel that it is relevant enough to mention, that what MidnightBlue states is found in the Halo series of fiction (including games), in the Sangheili species:
Sangheili warriors are the greatest warriors in the Covenant; however, their constant warfare is obviously not the environment in which to raise children. The best environment to raise children is with normal Sangheili parents, back on the Sangheili homeworld. But the genes for strength, intelligence, cunning, etc. are found in the warriors. Thus, tradition dicated that Sangheili warriors had the pick of the men and women on the homeworld, and were expected to reproduce as often as possible (female warriors, much less so, obviously...). Meanwhile, these children would be raised by the other biological parent and their spouse as their own child, while the genes of the warriors carried on into the next generation of Sangheili.