If you'd like another view of the Last Supper situation, here is one painted by Jacopo Bassano in 1542. He took a different approach than Leonardo DaVinci did. While Leonardo made them all in one long row, Jacopo went more for the 'simple fishermen' approach although the same complaints about authentic table, chairs, etc. still hold. Once again we see glass containers for the wine so you can SEE the red wine within, and this time there is a central pitcher. This isn't a real "table" though, in the sense that this entire group COULD have been eating around it. This is far more symbolic than realistic.

Visitor Opinion -
Notice the red head is the only one without a beard?

My response -
John was always said to be feminine, so he definitely would have been painted as a child-like guy. But I do agree that the character COULD be female. Also interesting is the obvious knife held in somebody's hand :)