Who is John Kennedy Jr.'s Real Father?

I've been a Kennedy fanatic since childhood. Like so many of our generation I like to think I learned a thing or two from Jackie about poise and style but lately I'm haunted by the realization that John Jr. bore virtually no resemblance to John Sr. or to any of the other Kennedy cousins. Surely Mrs. Kennedy brought a dark sensuality to his gene pool and this may explain his looks. However, when you look at Caroline, it's easy to see traces of both parents. She certainly fits into the general physical 'type' of the other Kennedy cousins we know...but not John. He stands out like a sore thumb in that crowd. Rumors have whirl led over the years about a possible affair that Jackie had with the elegant Fiat heir Gianni Agnelli. I have been searching photos of him and lo and behold, there we find the dark, regal qualities that are so apparent in John Jr. Could it be????? John was born on 11/25/60. I've been trying to find out more about Jackie's' activities early in 1960 when John Jr. would have been conceived. Since this is a pre-White House period, I have not been able to find anything about a possible liaison with Gianni at that critical time. The 1960 Primary Season began on 3/8/60 with the New Hampshire Primary. I believe Jackie was with her husband for the Primary season. Could she have taken a nice European vacation just prior to the onset of the primaries knowing that once they began she'd have little time for herself? Was this a period when their troubled marriage was in one of their many crises? I just find it tantalizing that we all may have been duped into thinking that John John was our American Prince when in fact he was Jackie's little oooooops? I apologize for the trauma this blasphemous notion may cause, but I can't get this notion out of my head and I would like any information that may help be reconcile the fact that John Jr. has NO Kennedy traits.