As a player, sometimes I want to settle down with an Orc and make a bunch of Half-Orc Babies, but seeing the word "species" gives me pause. I know in real life cross-breeding different species of animals rarely goes well and the children are as a rule sterile, so can i ethically bring a baby into the world that I know is going to be sterile and is probably doing to have serious health problems?

I don't get your problem here. Either the world that has half orcs declares if they are fine, or you are free to decide for yourself. Why bother yourself with some "knowledge" about the "real world"?