Complex sentence: Homosexuality in animals is seen as controversial by social conservatives because it asserts the naturalness of homosexuality in humans, others that it has no implications and is nonsensical to equate animal behavior to morality.
Split into simpler sentences: Homosexuality in animals is seen as controversial by some social conservatives, who believe that asserting the naturalness of animal homosexuality has an impact on the morality of homosexuality in humans. Others believe that it has no implications and is nonsensical to equate animal behavior to morality.