f the subtitle, "Being the Memoirs of a Somewhat Irregular Lady," evokes Fanny Hill, it's no accident. For although there's a science fiction story here, involving time travel, alternate history and super-longevity, the true subject of the book is sex. As the heroine, Maureen Johnson Long, says after one of many incestuous encounters: "What the world needs is more loving, sweaty and friendly and unashamed." One way or another this idea is endlessly repeated, out of the mouths of any number of the absurd characters populating this novel. The heroine, born in 1882, engages in what Heinlein imagines to be clever, iconoclastic conversation with her father before the turn of the 20th century, and later with husbands, friends and offspring; they are all so smug and self-righteous it sets the teeth on edge. While spewing out homilies on the proper conduct of life, they are generally engaging in activities more appropriate to a tale involving the Jukes or the Kallikaks. Heinlein seems to be on a mission, but he has made his message unpalatable. And far from being admirable, his characters are virtually moronsthey are totally closed, the world can teach them nothing. Not surprising: they're all inbred. Publication date is Heinlein's 80th birthday.