In this article, I'll walk through a basic Rails (4.0.0) setup for creating a nested resource for two models. Nested resources work well when you want to build out URL structure between two related models, and still maintain a RESTful convention. This code assumes you are running RVM to manage Ruby/Gem versions, and Git for version control.
$ rails new family
$ git init
$ git add .
$ git commit -am "new rails project"