Sicklygirl, that's funny you mention the holding it when you were younger.
I used to hold it for hours and hours as a youngster and was thinking the exact same thought just the other day...did I bring the UP on by my actions when I was a youngster.
Our 8yr old was following in my footsteps awhile back...he got really backed up/constipated and used to howl when he sat on the loo. Poor guy!