“Among high-earning couples, women have a smaller motherhood penalty, and fathers are getting a bigger bonus. [Among] lower-earning couples, moms are getting a larger penalty, and dads aren’t getting any bonus. Women who can least afford it pay the highest penalty for motherhood.”—MICHELLE BUDIG, sociologist at the University of Massachusetts, Amherst Concrete evidence about the consequences for mothers who opt out of the workforce to raise children has been hard to come by. Kate Weisshaar, a sociologist at the University of North Carolina at Chapel Hill, aims to change that. In a recent study, published in American Sociological Review, she scrutinized how employers respond to résumés from stay-at-home parents, uncovering surprising penalties. “When opt-out applicants are prevented from re-entering the labor market,” Weisshaar writes in her paper, “employers reinforce standards…