Humans mating successfully with Vulcans and Klingons was a pretty bad idea.
In terms of real biology, yes. In story and character terms, no.
The "interplanetary half-breed" is just a sci-fi take on the classic character who's torn between two different cultures, with the two sides of his or her own nature constantly in conflict. In real science, of course, successful interbreeding between species that evolved independently on different worlds is less likely than crossing a cat with an artichoke.