Python Parent Child Relationships in Google App Engine Datastore
What you're talking about is inheritance heirarchies, but App Engine keys provide for object heirarchies. An example of the former is "a banana is a fruit", while an example of the latter is "a car has a steering wheel". Parent properties are the wrong thing to use here; you want to use PolyModel.
I am trying to model a parent hierarchy relationship in Google App Engine using Python.  For example, I would like to model fruit.
So the root would be fruit, then a child of fruit would be vine-based, tree-based.  Then for example children of tree-based would be apple, pear, banana, etc.  Then as children of apple, I would like to add macintosh, golden delicious, granny smith, etc.
I am trying to figure out the easiest way to model this such that I can put in another entity of type basket a an entity of type fruit, or of type granny smith.
Any help would be greatly appreciated!
Thanks
Jon