Class variable propagates to child classes in Ruby

class_var.rb

class Parent
  def self.class_var
    @@class_var ||= self.name
  end

  def self.instance_var
    @instance_var ||= self.name
  end
end

class Children < Parent
end

puts "Parent.class_var:\t#{Parent.class_var}"
puts "Children.class_var:\t#{Children.class_var}"
puts ""
puts "Parent.instance_var:\t#{Parent.instance_var}"
puts "Children.instance_var:\t#{Children.instance_var}"

# Parent.class_var:   Parent
# Children.class_var: Parent
#
# Parent.instance_var:   Parent
# Children.instance_var: Children