Time Enough For Love by Robert A. Heinlein is a book about Lazarus Long, a guy who is very very very old. Maybe you shouldn’t read on if you want to read the book yourself, because I’ll tell you what happens.
Lazarus is this guy born sometime around 1920. Since his family has very good genes and in their lineage they all get very old, they take part in this project where they procreate among similar families, so they reach a very old age. By rejuvenation, they get to be even older. Lazarus is the oldest person around, and pretty much everyone is a distant relative of his, most people are descendants of him.
So far so good. Interesting in this book is whenever Lazarus describes settling down on a new planet, describes some of the customs there, some of the new technology they have. That’s the strong point of the book.
The weak point of the book is that the author was evidently very fixated on the procreation part and every female character in the book is exactly alike: promiscuous, complaining about all the taboos of society and she more than anything, wants to please lazarus and have his baby. And when I say every woman, I mean every woman: the slave he buys, who he refuses on account that she’s in reality in love with her twin brother; the girl he raises from when she was three; the women in the rejuvenation clinic; the computer that has been transplanted into a female body; his clones that got an extra X-chromosome; and oh, his mother, too. And don’t be upset by him sleeping with his own mother, it’s okay, because she’s pregnant when he does, so she can’t end up with a baby with a birth defect or anything…
You know, I think I’ll leave my review at that, because having read all 589 pages of this book, him sleeping with all these mentally identical women is really the only thing this is about. Have I mentioned that they’re all nudists in the future?
If you really want to read a Heinlein book, don’t read this, read Stranger In A Strange Land! (Or better yet, read something by Kurt Vonnegut.)