When Robert A. Heinlein's The Puppet Masters was originally published in 1951, it was censored by the publisher to remove various references to sex. The opening scene, where the protagonist is called urgently to HQ on an early morning hour, was re-written to remove all mention of his being in bed with a girl he had casually picked up. The published version did mention that the book's alien invaders cause human beings whose bodies they take over to lose sexual feeling – but removed a later section mentioning that after some time on Earth the invaders "discovered sex" and started engaging in wild orgies and even broadcasting them on TV in areas under their control. Thirty years later, with changing mores, Heinlein published the book's full, unexpurgated text. Heinlein's time-travel short story All You Zombies (1959) chronicles a young man (later revealed to be intersex) taken back in time and tricked into impregnating his younger, female self before he underwent a sex change. He then turns out to be the offspring of that union, with the paradoxical result that he is both his own mother and father. In Time Enough for Love (1973), Heinlein's recurring protagonist Lazarus Long – who never grows old and has an extremely long and eventful life – travels backward in time to the period of his own childhood. As an unintentional result, he falls in love with his own mother. He has no guilt feeling about pursuing and eventually consummating that relationship – considering her simply as an extremely attractive young woman named Maureen who just happens to have given birth to him thousands of years ago (as far as his personal timeline is concerned). The sequel, To Sail Beyond the Sunset (1987) takes place after Maureen had discovered the true identity of her lover – and shows that for her part, she was more amused than shocked or angry. Poul Anderson's 1958 novel War of the Wing-Men, centers on a species of winged intelligent creatures and sexual differences are central to its plot. Of the two mutually-hostile societies featured in the book, one practices monogamous marriage, while in the other there are every spring several days of a wild indiscriminate orgy – and a complete celibacy for the rest of the year. Ironically, both societies alike consider themselves chaste and the other depraved: "We keep faithful to our mates while they fuck around indiscriminately – disgusting!"; "We keep sex where it belongs, to one week per year where you are not really yourself. They do it all over the year- disgusting!". Humans who land on the planet intervene in the centuries-long war, by showing members of the two societies that they are not all that different from each other.
When Robert A. Heinlein's The Puppet Masters was originally published in 1951, it was censored by the publisher to remove various references to sex. The opening scene, where the protagonist is called urgently to HQ on an early morning hour, was re-written to remove all mention of his being in bed with a girl he had casually picked up. The published version did mention that the book's alien invaders cause human beings whose bodies they take over to lose sexual feeling – but removed a later section mentioning that after some time on Earth the invaders "discovered sex" and started engaging in wild orgies and even broadcasting them on TV in areas under their control. Thirty years later, with changing mores, Heinlein published the book's full, unexpurgated text. Heinlein's time-travel short story All You Zombies (1959) chronicles a young man (later revealed to be intersex) taken back in time and tricked into impregnating his younger, female self before he underwent a sex change. He then turns out to be the offspring of that union, with the paradoxical result that he is both his own mother and father. In Time Enough for Love (1973), Heinlein's recurring protagonist Lazarus Long – who never grows old and has an extremely long and eventful life – travels backward in time to the period of his own childhood. As an unintentional result he falls in love with his own mother. He has no guilt feeling about pursuing and eventually consummating that relationship – considering her simply as an extremely attractive young woman named Maureen who just happens to have given birth to him thousands of years ago (as far as his personal timeline is concerned). The sequel, To Sail Beyond the Sunset (1987) takes place after Maureen had discovered the true identity of her lover – and shows that for her part, she was more amused than shocked or ,angry. Poul Anderson's 1958 novel War of the Wing-Men, centers on a species of winged intelligent creatures and sexual differences are central to its plot. Of the two mutually-hostile societies featured in the book, one practices monogamous marriage, while in the other there are every spring several days of a wild indiscriminate orgy – and a complete celibacy for the rest of the year. Ironically, both societies alike consider themselves chaste and the other depraved: "We keep faithful to our mates while they fuck around indiscriminately – disgusting!"; "We keep sex where it belongs, to one week per year where you are not really yourself. They do it all over the year- disgusting!". Humans who land on the planet intervene in the centuries-long war, by showing members of the two societies that they are not all that different from each other.