By "truly addictive" I mean that they actually do remove an individual's ability to choose not to take them.
I have two brothers and one sister who are all drug addicts, heroine. I take the stance you bring forward but they claim it's physically impossible to kick it.
Banjo's link does present some evidence that the brain itself, the seat of personality, can be altered, and so alter the personality. Perhaps this is so for heroin as well. The concept is not really controversial in and of itself, but the implications could be very controversial.