Caplan (economics, George Mason U.) claims that modern parents are not having enough kids. A father himself, Caplan draws on recent research to show that heredity is a bigger factor than parenting in a child's life, and translates this into good news for parents: Whatever parents do, the kids will probably turn out OK! The book offers a parent's guide to behavioral genetics, with several chapters devoted to explaining current research in the field and its implications for parenting. Other reasons for having more kids: kids are safer now than in the 1950s, and more kids means more workers to keep Social Security and Medicare alive. The book concludes with selfish guidelines for want-to-be grandparents, and a final chapter reviewing fertility technology. The author is a blogger at one of the Wall Street Journal's Top 25 Economic Blogs. Annotation ©2011 Book News, Inc., Portland, OR (booknews.com)