has_one relationship to the same class

I have the following `Person` class that has a parent that is also another Person. I can't seem to figure out how to get the relations to work. ``` class Person < ActiveRecord::Base attr_accessible :mom, :dad has_one :mom, :class_name => 'Person', :primary_key => "mom_id", :foreign_key => "id" has_one :dad, :class_name => 'Person', :primary_key => "dad_id", :foreign_key => "id" end ``` I have added "mom_id" and "dad_id" as integers to my model with a migration. However, when I use the `rails console`, I'm not able to access `mom` or `dad` attributes after settings the `mom_id` and `dad_id`. They still return `nil`. Any pointers to what I am doing wrong?