EA, a Question About Sims 4 Game Engine

I think they built their own framework to run this game, although I wonder if they recycled the previous engine for the Sims 4. Interactions between Sims are a behavior AI and easier to change than physics or routing or rendering. That is, the engine will have universal rules for it's shading and collision detection, how memory is managed and animations are handled. I think that some basic logic structures from previous Sims titles are apparent, and the "Smart/Emotional" AI is just an extension of the core(engine) scripting. I suspect the 'new' Engine is just a re-incarnation of the Sims 2 and 3(3D engines), where as Sims 1 seems like it runs on 2D isometric engine logic, so it's unique. Also, it, the Sims1 engine, could be the intellectual property of it's creator, Will Wright.