Yes. I want to be able to demonstrate a one-to-one relationship between Person and Email, and Person and Bio. Some applications might support a Person with multiple email addresses, or a Person with multiple bios, in which case, a one-to-many relationship will be ideal.

There might be applications where the necessary data and optional data are separated into different models, so that the essential data is first displayed to the user and if optional additional data is available, it can be retrieved later. This will speed up retrieval of essential-only data for a large database.