The transition to parenthood and living with young children are also associated with lower rates of adult substance use (Chilcoat & Breslau 1996). Yet, again, the effects of parenthood are not unequivocally positive because parents tend to exercise less and weigh more than nonparents (Bellows-Riecken & Rhodes 2008, Nomaguchi & Bianchi 2004). In fact, obesity risk for men and women increases with each child they have (Weng et al. 2004). This pattern of weight gain is similar to that found with other adult relationships. According to Christakis & Fowler (2007), having an obese friend increases one’s own risk of becoming obese by 57%, and having one obese sibling increases obesity risk by 40%.
