That isn't the point though. When you come down to it, the point of existence as an animal in the animal kingdom IS to reproduce. It doesn't matter where you're from. The barriers that lead to reproduction, social status, sexuality, wealth, etc., is what is the only difference between us and animals. If it weren't for social norms, we'd be reproducing like rats.
Hell, studies have shown humans ARE evolving, just at a slow rate. So simply adopting isn't necessarily the answer. Being gay prevents evolution due to how it does not allow for mutation to occur in offspring, because you don't have any, hence it is NOT normal, but everyone should have already learned by like preschool being not normal is not wrong, (see original comment about how I feel about that).