first you must define pedo. In some societies on earth today a 13yr old girl is old enough to marry. Some tribal societies (before the Mormons got to them) held that children should be iniated to sex by an older relative, others by the older children.
In the US they would all be classed as pedos.
Given the range of variation shown, I'd wager "Nurture". The fact that a large percentage pedos were themselves victims also supports it.