Oh for crying out loud, so lets pin a sexual offender label on all three of them for the next ten years. While its not appropriate I just don't see the interaction of children under 9 to be as big a deal as this. they knew it was wrong or they wouldn't have been hiding.
Were they need to watch is the 8 year olds contacts, brother cousin Uncle or family Friend. and even then there is no assurance of misdeeds. it could be a creative kid mimicking what he has seen and heard in the media.
Now I know little boys and girls have instances like this, so why don't we hear about that on the news ?