It's hard to say to what extent that is true. The organization definitely encourages JWs to practice willful ignorance by labeling scientific information pertaining to evolution as being "satanic propaganda". So there is definitely the tendency for JWs to be ignorant concerning most of the facts about evolution. Then the "spiritual routine" that JWs are encouraged to keep up, greatly limits their free time to pursue self-education through personal research into non-religious matters outside Watchtower literature. Higher education is discouraged. So there's indeed a confluence of factors encouraging JWs to be ignorant.
But we must keep in mind that a significant percentage of JWs are not born-ins but adult converts. Before becoming JWs, many of these adult converts may have already been exposed to the information that born-in JWs have never seen. So I would say that the institutionalized ignorance plaguing JWs would be more pronounced among born-ins.
I would say that there is definitely a higher incidence of ignorance among JWs than among non-JWs. But I don't know how typical it is.