Although the thrust of this article seems to be drug - drug interactions, I wouldn't doubt a genetic predisposition. Enter serotonin syndrome and (CYP2D6 or cytochrome P450) into PubMed's query box. A lot of school shootings, maybe most, were done by kids on SSRIs. If their defense was up to snuf, they would be tested for this genetic variation for trial, appeal or parole board.
I'd be interested in seeing the hard numbers, but then again, if they didn't have "problems", they probably wouldn't be on the meds.
Did the SSRIs affect the behavior? Without, would a lonely suicide be the course of action, or did the SSRIs change the course action that to that of TROP practitioner?
I just hate to see beneficial drugs be maligned and/or taken off the market because the wrong people got them.
That's not to say that better qualifying criteria can't be put in place.
I've seen it happen with first dose on a medication...
Drug interactions most certainly can cause it as well.