In the current introspection data, the various gtk_radio_button_new_* constructors take an existing group or widget. These all allow to pass a "None" widget or group list, so that it becomes much easier to build a radio button list in a loop (pass in None the first time, and the previously created button in all other iterations).

The "allow-none" is missing, though, so you currently have to work around this with something like

   b = None
   for option in my_options:
       # use previous radio button as group
       if b:
           b = Gtk.RadioButton.new_with_label_from_widget(b, option)
       else:
           b = Gtk.RadioButton.new_with_label([], option)

It should just work with

   b = None
   for option in my_options:
       # use previous radio button as group
       b = Gtk.RadioButton.new_with_label_from_widget(b, option)

but that currently throws

TypeError: unbound method new_with_label_from_widget() must be called with RadioButton instance as first argument (got NoneType instance instead)