While these are generally frowned upon, and viewed akin to beastiality by most, interspecies relationships CAN happen! Half-Elves, Half-Orcs, Half-Drow, etcetera can and do exist in this world. However, all offspring are infertile, and as such are unable to pass on the family lineage. For this reason, you don’t commonly find too many interspecies relationships, or too many kin that were the result of a planned pregnancy.
Half-Breeds exist all over the world, most commonly Half-Elves and Half-Orcs. They are seen as mutts, not belonging to any certain race. However, they can use this to their advantage in racially charged situations, as they commonly deny the lineage on both sides of the equation. It is not uncommon to find Half-Breeds traveling together as groups of adventurers.