Behaving presents an overview of the recent history and methodology of behavioral genetics and psychiatric genetics, informed by a philosophical perspective. Kenneth F. Schaffner addresses a wide range of issues, including genetic reductionism and determinism, "free will," and quantitative and molecular genetics. The latter covers newer genome-wide association studies (GWAS) that have produced a paradigm shift in the subject, and generated the problem of "missing heritability." Schaffner also presents cases involving pro and con arguments for genetic testing for IQ and for Attention Deficit Hyperactivity Disorder (ADHD).

Schaffner examines the nature-nurture controversy and Developmental Systems Theory using C. elegans or "worm" studies as a test case, concluding that genes are special and provide powerful tools, including "deep homology," for investigating behavior. He offers a novel account of biological knowledge emphasizing the importance of models, mechanisms, pathways, and networks, which clarifies how partial reductions provide explanations of traits and disorders.

The book also includes examinations of personality genetics and of schizophrenia and its etiology, alongside interviews with prominent researchers in the area, and discusses debates about psychosis that led to changes in the DSM-5 in 2013.

Schaffner concludes by discussing additional philosophical implications of the genetic analyses in the book, some major worries about "free will," and arguments pro and con about why genes and DNA are so special. Though genes are special, newer perspectives presented in this book will be needed for progress in behavioral genetics- perspectives that situate genes in complex multilevel prototypic pathways and networks. With a mix of optimism and pessimism about the state of the field and the subject, Schaffner's book will be of interest to scholars in the history and philosophy of science, medicine, and psychiatry.