Homosexual activity in animals is never monogamous as the breeding and care of offspring still depend on both sexes playing a role in the care of offspring. The only animals that exhibit monogamy are exclusively male-female for the production and care of offspring.
the statement that homosexuality is natural because animals do it does not apply to monogamous relationships, which is inherently what marriage is about.
"Male penguin couples have been documented to mate for life, build nests together, and to use a stone as a surrogate egg in nesting and brooding.
In 2004, the Central Park Zoo in the United States replaced one male couple's stone with a fertilized egg, which the couple then raised as their own offspring.German and Japanese zoos have also reported homosexual behaviour among their penguins. This phenomenon has also been reported at Kelly Tarlton's Aquarium in Auckland, New Zealand.
"Humans have created the myth that sexuality can be justified only by reproduction, which by definition limits it to hetero sex," says Michael Bronski, author of The Pleasure Principle: Culture, Backlash, and the Struggle for Gay Freedom.
"But here is an animal society that uses homosexuality to improve its social life." "
"Zoologists and biologists now have solid evidence that monogamous pairs of animals are not always sexually exclusive. Many animals that form pairs to mate and raise offspring regularly engage in sexual activities with extra-pair partners."
"Sometimes these extra-pair sexual activities lead to offspring. Genetic tests frequently show that some of the offspring raised by a monogamous pair come from the female mating with an extra-pair male partner. These discoveries have led biologists to adopt new ways of talking about monogamy:"
The presence of same-sex sexual behaviour was not scientifically observed on a large scale until recent times. Homosexual behaviour does occur in the animal kingdom outside humans, especially in social species, particularly in marine birds and mammals, monkeys, and the great apes. Homosexual behaviour has been observed among 1,500 species, and in 500 of those it is well documented.
To turn the approach on its head: No species has been found in which homosexual behaviour has not been shown to exist, with the exception of species that never have sex at all, such as sea urchins and aphis. Moreover, a part of the animal kingdom is hermaphroditic, truly bisexual. For them, homosexuality is not an issue.
Georgetown University professor Janet Mann has specifically theorised that homosexual behaviour, at least in dolphins, is an evolutionary advantage that minimizes intraspecies aggression, especially among males.
- Mounting of one female by another is common among cattle. (See also, Freemartin. Freemartins occur because of clearly causal hormonal factors at work during gestation.)
- Bonobos in zoos. After studying the primates for his book Bonobo: The Forgotten Ape, primatologist Frans de Waal, a professor of psychology at Emory University in Atlanta, says that such expressions of intimacy are consistent with the homosexual behaviour of what he terms "the erotic champions of the world." "Same-sex, opposite-sex bonobos just love sex play," de Waal said in an interview. "They have so much sex, it gets boring."
- Homosexual behaviour in male sheep (found in 6-10% of rams) is associated with variations in cerebral mass distribution and chemical activity. A study reported in Endocrinology concluded that biological and physiological factors are in effect. These findings are similar to human findings reported by Simon LeVay.
Approximately eight percent of [male] rams exhibit sexual preferences [that is, even when given a choice] for male partners (male-oriented rams) in contrast to most rams, which prefer female partners (female-oriented rams). We identified a cell group within the medial preoptic area/anterior hypothalamus of age-matched adult sheep that was significantly larger in adult rams than in ewes...
- Male bighorn sheep are divisible into two kinds: the typical males among whom homosexual behaviour, including intercourse, is common and "effeminate sheep", or "behavioural transvestites", which are not known to engage in homosexual behaviour.
Animal sexual behaviour - Wikipedia, the free encyclopedia
I also believe there are currently homosexual humans who are in monogamous relationships and are in the process of caring for and rearing children. Also you do not need to be in a monogamous relationship to raise children there are plenty of single parents out there doing a fine job of raising their children.
Then again you choose to ignore the polyamorus who I am sure at least some of them are raising children.