title: Rails Question: belongs_to with STI -- how do i do this correctly?
body: <p>I've been playing around with STI and belongs_to / has_many relationships and I'm a bit confused.</p>
  
  <p>I have a few questions based on a model configuration similar to:</p>
  
  <pre><code>class Parental &lt; ActiveRecord::Base
  end
  
  class Mother &lt; Parental
      has_many :babies
  end
  
  class Father &lt; Parental
      has_many :babies
  end
  
  class Baby &lt; ActiveRecord::Base
      belongs_to :?????? 
  end
  </code></pre>
  
  <ol>
  <li>What should <code>Baby</code> belong_to?</li>
  <li>In terms of a migration, what should i name/add for foreign key on
  the <code>babies</code> table?</li>
  <li>I've had a hard time researching this, is there a definitive source
  that explains this?  The API docs did not seem to hit it on the head
  OR i missed it (which is totally possible).</li>
  </ol>
  
  <p>My first thought is add <code>parental_id</code> to <code>babies</code> along with a method like <code>Baby#owner</code> that does the following:</p>
  
  <ul>
  <li>Hits self.parental </li>
  <li>Determines the parental's type</li>
  <li>Returns the correct type of parental (could be a mother, could be a father)</li>
  </ul>
  
  <p>Thank you!</p>