“…Children who start school later tend to score higher on standardised achievement tests throughout the school years (Bedard & Dhuey, 2006;Crawford, Dearden, & Meghir, 2007;Elder & Lubotsky, 2007;Fredrikson & Öckert, 2006;McEwan & Shapiro, 2008;Puhani & Weber, 2007;Strom, 2004). Gender differences in school readiness, particularly in regards non-cognitive skills, also exist with boys tending to be more aggressive (Hood, 1996;Zimmer-Gembeck, Geiger, & Crick, 2005;May & Kundert, 1997) and displaying fewer prosocial and helping behaviours (Romano, Tremblay, Boulerice, & Swisher, 2005;Zimmer-Gembeck et al, 2005) than girls. Furthermore, the absence of siblings has been found to have a positive effect in a child's cognitive development (Falbo & Polit, 1986;Modry-Mandell, Gamble, & Taylor, 2007).…”