Extremely confused by what I found on my son's PC!?

Well yesturday my laptop broke down.. so I had to use my 11 year old son's laptap... and I am shocked at what I found. He had literally hundreds of pictures and videos of old ladies, aging from around 65 upwards! There was also some pornographic type pictures of this nature also... .. What could this mean??? I nevre got the impression before that he was perverted... he is only 11!