[robertpaulsen]

"Some addicted drug users look back to cigarettes as the start of it all"

Let me see if I get this right. Smoking a Marlboro can be the start of addiction to other drugs, but smoking marijuana cannot?

[MrLeRoy]

Smoking a Marlboro can be the start of addiction

Use is not the same as addiction.

to other drugs, but smoking marijuana cannot?

Either one can be chronologically prior to the use of other drugs. If that makes marijuana a "gateway drug" it also makes tobacco a "gateway drug."