Cheryl Erwin is a former commentator for “Parenting with Cheryl Erwin” and is a licensed marriage and family therapist with more than 25 years of experience in working with parents and children. She is also the author or co-author of several books on parenting, including “Positive Discipline: the First Three Years,” “Positive Discipline for Preschoolers,” and “Positive Discipline for Single Parents.”