In this article, I'll walk through a basic Rails (3.2.x) 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. .
$ mkdir family # create rvm gemset
$ echo "rvm use --create ruby-1.9.2@family" > family/.rvmrc
$ cd family # install rails
$ gem install rails # create new rails project
$ rails new . # version control