“…Finally, the repetitive behavior domain is quite diverse, including intense restricted interests, simple repetitive motor mannerisms, inflexible rituals or routines, or preoccupation with parts of objects, with each child only required to show two of these positive symptoms (American Psychiatric Association, 2000;Richler et al, 2007Richler et al, , 2010. Recent work in sibling pairs affected with autism suggests that individual symptom domains or sub-domains may be separately inherited, particularly in the case of repetitive behavior (Georgiades et al, 2007;Lam et al, 2008;Smith et al, 2009;Tadevosyan-Leyfer et al, 2003).…”