The Sims DE Magazine wrote a small article about genetics in The Sims 4. Thanks Crinrict for providing the translation of this article!
Since the Sims characters is now driven by DNA, CAS now has a new feature (our favorite): The family genetics. When creating a new Sim you can do that like you always did and start at the beginning or use the new functionality and randomize children of two existing Sims – finally hair color isn’t the only thing that kids inherit from their parents. They actually resemble them. In the same way you can create parents and siblings. Your family actually looks like certain physical features are passed on.