I grew up Catholic. Went to Catholic School every day. Converted to Jehovah's Witnesses at 17. There are many similarities.
1.Catholicism:Only a clergy member can interpret the bible correctly. We were discouraged from reading it. At mass we had missal books.
2.Jehovah's Witnesses:Only the governing body can interpret the bible correctly. We were discouraged from reading it without the aid of a Watchtower.
And yes, most of the Witnesses I knew were ex-Catholics.
I could go on and on.