In western culture the forbidden fruit was an apple. This was the case because the Latin word for apple and evil are similar in the singular (malum — apple, malus — evil). Thus the pun has continued ever after.
In the Jewish tradition the fruit was a fig which makes the use of fig-leaves as the fabric for the first cover-up in human history even more interesting. In the art below, Karen Yurkovich has placed an apple on a fig branch. I do not know if she is aware of the irony but suspect that she intended that very subtle hint toward the story of the fall.