promoting an even more "alternative" lifestyle than mere homosexuality- Bestiality.
Try it from a religious point of view. There are people and then there is everything else, Land animals, birds, fish, etc., all are "beasts" or "the beasts."
An intelligent species would be people, as long as who you are with qualifies as sapiens, technically there is no beastiality.
There was that one stupid species, the one who kidnapped Geordi, (Paknins?) they might not be good to have sex with.
(The Church would still perfer you were married though)
