You can completely eliminate sex, and it won't make much of a difference to the game.
However, there are far too many things I'd call "kid unfriendly". They are everywhere, and to remove them all would be to play a totally different game (not to mention you would probably not want your players to read the players book)
In mage:
- Magic to break a part of your soul
- Magic to steal anothers soul/trap it
- Magic to consume another, causing terrible pain, to regain mana
- Live sacrifices (of animals/humans) for mana
- Magic to steal life from another person, with the intent of living longer
- Magic to animate corpses
- Magic to manipulate people, changing them deeply (/revive them as a obsessed copy of themselves)
- Magic to decompose an enemy's living body
- Magic to curse people/ their decendants
- The whole hubris thing: Rules specifically designed for characters that slowly lose their connection to the world and fall prey to hubris (aka the morality system)
- Rules to create a new mind, including the possibility of the mind going insane for lack of human contact or the possibility of the said mind suffering with its "death" after the spell ends
- Very graphical descriptions of violence in almost arcana (the 10 "types" of magic)
(I stopped because I got tired, but there is much more ...)
In wod in general
- Ghosts (aka: lost souls, having lost much of their humanity, kept from release by obsession or terrible regret)
- Rules pertaining madness (that are hard to escape: they are associated with the morality system)
- A general mood of violence and hopelessness