Book excerpt: In Selfish Reasons to Have More Kids, contrarian economist Bryan Caplan argues that we've needlessly turned parenting into an unpleasant chore, and don't know the real plusses and minuses of having kids. Parents today spend more time investing in their kids than ever, but twin and adoption research shows that upbringing is much less important than we imagine, especially in the long-run. Kids aren't like clay that parents mold for life; they're more like flexible plastic that pops back to its original shape once you relax your grip. These revelations are wonderful news for anyone with kids. Being a great parent is less work and more fun than you think—so instead of struggling to change your children, you can safely relax and enjoy your journey together. Raise your children in the way that feels right for you; they'll still probably turn out just fine. Indeed, as Caplan strikingly argues, modern parents should have more kids. Parents who endure needless toil and sacrifice are overcharging themselves for every child. Once you escape the drudgery and worry that other parents take for granted, bringing another child into the world becomes a much better deal. You might want to stock up.