: The NPC Distribution & Beauty Standards menu allows you to set how the game automatically generates the population's attractiveness and body types.
: As of v4.0, you can use the Real Face Import feature to generate characters based on real photos of yourself or celebrities. LifePlay
This script snippet demonstrates how to generate a temporary person and initiate a choice-based scene. : The NPC Distribution & Beauty Standards menu
If you are looking to build more complex features, you can utilize these existing game systems: LifePlay