Update: This has nothing to do with relationships between Sims in the game. There will still be Brothers, Cousins, Grandfathers etc. (See the Full List). The thing that we won’t have is the Family Tree User Interface that shows all the Sims that are currently living (and who are dead) who belong and/or are a part of that family.

Pic from The Sims 3 Forum

Crinrict, SimTimes & @Renssies confirmed that during The Sims 4 Presentation in Germany, SimGuruLyndsay told them that there are NO Family Trees in The Sims 4! Kinda a let down, don’t you think? :/