"Do you honestly think marriage and reproducing offspring is the reason animals have sex?"
What I was saying, is that Animals do not have the ability to enjoy sex as they act out of instinct for reproduction.
"Some animals have one mate for life, others have multiple partners and homosexuality is well documented in the animal kingdom. Some are even able to change sex, and/or have both sex organs."
This is absolutely irrelevant to Humans as Humans have a Brain, a conscience and free will to make choices. Animals act only out of instinct and have no rational thought process, and for eg only kill enough to Eat for their immediate needs unlike Humans. Also, using a Lion as an example, if the dominant Male of a Pride is killed by a stronger Male it takes over and kills all offspring and becomes leader!
Does that happen in Human Society?
What would happen if animals that needed a Mate decided to be Homosexual?
Homosexuality may be a natural occurrence but in the Animal World would be considered a deformity or abnormality as it does not help the survival of any Species!