Amidst all the sexual innuendo and other vulgarities of the Attitude Era was the feud between the Undertaker and his brother, Kane. The later was, of course, so named as a direct reference to the biblical tale of Cain and Abel. The sons of Adam and Eve, Cain would eventually kill Abel out of jealousy and anger before being condemned by God to wander the earth. As such, Cain is generally looked at as the Evil brother. So when it came time to introduce the Undertakers long lost brother who was previously believed to be dead, it didnt take too much imagination to reveal that this brothers name was, in fact Kane (as a side note, what parent would name their child Kane?). Now, while this is an easy reference to pick up on for anyone with even a semblance of religious knowledge, it may not be so apparent to people from an extremely secular or non Judeo Christian background. WWE took liberties with the biblical inspiration, of course, eventually divulging that it was the Undertaker who apparently set the fire that killed Kane. But then basic good brother / bad brother story is pretty obviously right out of Sunday school lessons.