Do I need to have a "references" column in both my Question and Answer models?

Question

If I have a has_many and belongs_to relationship between Questions and Answers:

class Question < ActiveRecord::Base
  has_many :answers
end

class Answer < ActiveRecord::Base
  belongs_to :question
end

Do I also need to modify the migration files to use "references":

class CreateAnswers < ActiveRecord::Migration
  def self.up
    create_table :answers do |t|
      t.text :body
      t.references :question

      t.timestamps
    end
  end

  def self.down
    drop_table :answers
  end
end

class CreateQuestions < ActiveRecord::Migration
  def self.up
    create_table :questions do |t|
      t.text :body
      t.references :answer

      t.timestamps
    end
  end

  def self.down
    drop_table :questions
  end
end

Answer 1

The foreign key only goes in the model that belongs_to the other.