BOOK REVIEW / Members at length: 'Life Force' - Fay Weldon: HarperCollins, 14.99 pounds

FAY WELDON has been fretting about sociobiology. What if we are predetermined to act in the best genetic interest of the human race? If feminist ideals count for nothing, if men must sow their seeds as indiscriminately as possible, if women must continue to value quality of sperm over quantity, what are the implications for NW1?

To explore these troubling issues she has invented the priapic and devilishly unconvincing Leslie Beck, veteran of two troubled marriages and father of more daughters than his wives imagined in their worst nightmares. The story is narrated in the usual gossipy, whisky voice by a former mistress, Nora, now underemployed in a Richmond estate agent's - although it is not quite as straightforward as all that, for the first pages would appear to be narrated by Marion, a gallery owner who was once his au pair, or to be Marion's version of events as Nora imagines they must have looked to her.

As this watered-down post- modern trickery continues, it becomes as difficult to distinguish the different fictions as it is to understand why anyone would want to bother. The plot is at the same time too complicated (Nora is forever having to stop and give bed-hopping recaps) and too simple (the fornicator on top is always Leslie). The ideas are recycled, the ironies leaden, the female characters clones who protest too much about the length of their hero's member.

Although there are times when Leslie threatens to become ambiguous, his creator always manages to slap him back into line with a few smug agony- aunt aphorisms. No one is allowed to have fun in this sour grapes anti-romp, least of all the reader. But perhaps that's the whole point.