Do coffee beans, cocoa beans and cocain all come from the same plant?
No, they all are produced on different plant forms. They all require labor intensive harvest and preparation prior to consumption (except for coca leaves). Sometime that is child labor. They are all tropical in origin. All are to some degree psychoactive. Edit; oh yeah, the coffee and cocoa crops are grown on trees, I believe that coca is grown on a shrub form. And as one answer noted, they are way distant connected evolutionarily. They are all flowering plants. Coffee is from Africa and Asia, while Coca is South American, Cocoa is likely Amazonian. Very different distributions. To confuse you further, all things are related at the level of diversity among life; we are all related to all else alive through the determination to live.