do you really only need to take joy once to become a joy mutant?

i sort of figured that the people who became joy mutants, got addicted and took it lots of times, rather than taking it once and being fated for mutanthood. this irked me while i was playing hopeful and other games where taking joy even once has consequences. is joy really that strong?

meta-wise, i thought having to >!never!< >!take joy !<>!for true endings !<was more of a reward for challenging yourself rather than it making buddy and brad joy mutants. they had already taken it several times before, as buddy comments on joy "not tasting good" to >!marty !<, and brad being obvious.