Theyare half brothers
VOILENCE AND HIS BROTHER THE UnDeRtAkEr
The Undertaker doesn't have son, although his Kayfabe brother in the WWE is Kane.
Kane is undertakers little brother in wwe but off-set they are not even related
Kane is Undertakers storyline half-brother.
He is the brother of the Undertaker in smack down and Kane is in RAW. they both a scary and a good fighters. [:
Jake The Snake RobertsBatistaJohn CenaRandy OrtonMichelle MccoolEvan bourneTed Debiesa JrShawn MichaelsNikoli VolkovMillion Dollar ManMarty JannettyEddie GuerreroLex LugerHarley RaceChris JerichoGeorge The Animal SteelGreg The Hammer ValentineRey MysterioRick StienerDr. DeathStingTatankaTerry TaylorNikita KoloffPaul BearerGlacierBryan BlairTully Blanchard (he is actually a minister of a church)AfaBilly GrahamRikishiAJ StylesTriple HRoad Warrior HawkRoad Warrior AnimalCM PunkBuff BagwellThe Rock
He is buried alive by his brother Kane with help of Nexus
In 1997, Paul Bearer brought Kane to the WWE ( then WWF ) to challenge the Undertaker. It was revealed that he was the Half-Brother of the Undertaker, and later on that Paul Bearer is Kanes father.