Generating Siblings Based on a Reference Character

This is a Nano Banana Pro prompt for generating siblings of a character based on a reference illustration.

It works by simply specifying sister or brother within the prompt.
It is likely possible to specify mother or grandfather as well.

It allows specifying multiple people, not just one.
It also allows specifying individual characteristics.
The first image was output with the following:

[Siblings to generate]

Sizes can also be customized, such as vertical, horizontal, or square, not just the original.