Ever heard of the program "Faces" that the police use to ID criminals?
It could be done in 3D, relatively easily . . . . if someone were to write the code.
How? Well, take the example that I have attached and run polygon>smooth on it . . . . then consider what would happen if you could introduce functions to change the facial features by manipulating the location of the points in the basic, un-smoothed head, to get the desired results, i.e. larger or different shaped nose, etc. . . .