In the novel, The Forever War, the protagonist travels light years from Earth to fight battles then returns to Earth each time with decades or centuries of time having past. One time he returns to find that most people are Gay and Straight people often undergo conversion to "fit in." Later when he and his company of "gay soldiers" return they find that the "gay fad" ended a century earlier when the species practically died out. The lesson? Homosexuality is an evolutionary dead end.
