in theory its possible. but the only genetic splicing we've been able to do have been very genetically simple (jellyfish, squirrels, thats all I can remember). it involves a process of RFLPs, plasmids and bacteria used with polymerase chain reactions to insert wanted DNA into host DNA strands. Its sketchy and extremely hard to pinpoint exactly what codons code for what psychoactive traits in the marijuana and cocoa plant. It would take some SERIOUS druggies to do it, with access to some pretty advanced scientific equipment