“…Some exceptions existed in that four studies recruited not only biological parents but also grandparents, foster parents, stepparents, and relatives (Gross et al, 2003;Gross et al, 2009;Nicholson, Anderson, Fox, & Brenner, 2002;Treacy et al, 2005). Both mothers and fathers were recruited in 19 studies (Blakemore et al, 1993;Fanning, 2007;Gross, Fogg, & Tucker, 1995;Hanisch et al, 2010;Hutchings et al, 2007;Irvine, Biglan, Smolkowski, Metzler, & Ary, 1999;Larsson et al, 2009;Matsumoto et al, 2007;Matsumoto et al, 2010;McGillicuddy, Rychtarik, Duquette, & Morsheimer, 2001;Nixon & Singer, 1993;Pisterman et al, 1992a;Pisterman et al, 1992b;Schultz et al, 1993;Taylor et al, 1998;van den Hoofdakker et al, 2007;Wang, 2005;Webster-Stratton, Kolpacoff, & Hollinsgworth, 1988;Wolfson et al, 1992). In contrast, 12 studies recruited either the mother or the father, but not both parents (Bradley et al, 2003;Cunningham, Bremmer, & Boyle, 1995;Fantuzzo et al, 2007;Gallart & Matthey, 2005;Gardner et al, 2006;Joachim et al, 2010;Martin et al, 2003;Morawska & Sanders, 2009;Patterson et al, 2002;Spaccerelli, Cotler, & Pehnman, 1992;Turner et al, 2007).…”