One in four men are pedophiles according to plethysmographic studies of normal men:

Hall, G.C.N., Hirschman, R., & Oliver, L.L. (1995). "Sexual Arousal and Arousability to Pedophilic Stimuli in a Community Sample of Normal Men," Behavior Therapy, 26, 681-694.
>"Consistent with previous data (Barbaree & Marshall, 1989; Briere & Runtz, 1989; Fedora et al., 1992; Freund & Watson, 1991), 20% of the current subjects self-reported pedophilic interest and 26.25% exhibited penile arousal to pedophilic stimuli that equaled or exceeded arousal to adult stimuli. [...]
>Eighty subjects completed the study. [...] Twenty-six subjects [approximately 33%] exhibited sexual arousal to the child slides that equaled or exceeded their arousal to the adult slides.
>[...] a sizable minority of men in normal populations who have not molested children may exhibit pedophilic fantasies and arousal. In recent studies, 12 to 32% of community college samples of men reported sexual attraction to children (B &R, 1989, H,G & C. 1990) or exhibited penile response to pedophilic stimuli (B&M, 1989, F et al, 1992, F&L, 1989, F & W, 1989). Thus, arousal to pedophilic stimuli does not necessarily correspond with pedophilic behavior (Hall, 1990; Schouten & Simon, 1992), although there are arguments to the contrary (Quinsey & Laws, 1990)."