“…A review of the literature reveals a clear effect of sibling similarity in a variety of adolescent adjustment outcomes. For example, there is evidence that siblings are similar in risky sexual attitudes and behaviors (McHale, Bissell, & Kim, 2009), tobacco use (Slomkowski, Rende, Novak, Lloyd-Richardson, & Niaura, 2005), academic achievement and substance use (McGue & Iacono, 2009), externalizing behaviors and delinquency (Rowe, Rodgers, & Meseck-Bushey, 1992), and self representations (Gamble, Yu, & Card, 2010). Following basic social learning principles, evidence is beginning to point to stronger sibling similarity when siblings are the same gender, close in age, and, to a lesser extent, when they are genetically similar (McGue & Iacono, 2009; McHale et al, 2009; Rowe & Gulley, 1992).…”