An unwieldy assemblage of information on the varied elements--from genes to neurotransmitters to early life experiences--that are believed to contribute to personality. Science writer Gallagher (The Power of Place, 1993) has assembled but not digested a huge amount of information on the complementary roles of nature and nurture in forming our individual identities. Her book centers on a woman identified as Monica. Monica was studied from her sensually deprived infancy (when an esophageal defect necessitated tube feeding and a depressed mother neglected her) and on into her unpredictably happy, successful adulthood--a success psychologists say is due to an inborn temperamental gift that we might call charisma. Pursuing this and many other studies (but without sourcing them), Gallagher brings out a particularly interesting point: that research has found nature and nurture to be linked in a two-way relationship. For instance, experience can actually change neurotransmitter patterns in the brain; conversely, our inborn temperament can influence what kinds of experiences we have. But Gallagher lacks a strong framework or point of view; she roams all over the psychological map, from memory to the unconscious to the artistic temperament. Too often, she gives an on-the-one-hand/on-the-other summary of the facts that leads to no conclusion other than the fairly useless one often repeated to her by researchers: We still don't know how much our genes and our environment contribute respectively to our selves. Further, she relies heavily on models that measure temperament on a range of axes, such as extroversion and agreeableness. But while Gallagher protests how complex personality is, this theory sounds like a simplistic building-block approach: Mr. X may have a large dose of extroversion, a touch of irritability, etc. Researchers recently announced the identification of a gene they say influences temperament. Only the future will tell us what Gallagher unfortunately can't.