may be due to genetic factors (Silventoinen et al., 2007; van den Berg & Boomsma, 2007). Physiologic and environmental signals appear to have more of a permissive role that prevents pubertal onset in the presence of adverse conditions such as inadequate nutrition (Roseweir & Millar, 2009), and may accelerate pubertal onset in the presence of some kinds of social stressors (Tither & Ellis, 2008). Kisspeptin is a protein triggering the pubertal upsurge in GnRH production, in part through acting as a mediator by which environmental signals are transferred. However, what signals the up regulation of Kisspeptin is not yet known (Gottsch, Clifton, & Steiner, 2009; Navarro, Castellano, García-Galiano, & Tena-Sempere, 2007).
