How to manage multiple roles using polymorphic association in rails?

I am using devise for authentication and finding a way to get out of this.

class User < ActiveRecord
  belongs_to :loginable, polymorphic: true
end

class Parent < ActiveRecord
  has_one :user, as: :loginable
end

class Teacher < ActiveRecord
  has_one :user, as: :loginable
end

Can I explore same design having user multiple roles ?. So that he can login as Teacher and Parent both?