Cost of Inheritance Java (Android)
It's the correct, and probably only, Java way. In Java all calls are virtual anyway unless you use final all over the place, but that means you couldn't even use interfaces. So most calls will probably be virtual dispatch whatever you do. Inheritance does not incur any other significant penalty.
Besides, Android devices are generally so powerful that trying to sqeeze out tiny bits of performance at the cost of readability and maintainability of the program is almost certainly not needed. In fact, most android devices are almost as powerful as web servers that do the same things in much slower PHP and still manage thousands of users while the Android device serves one.
I am building an extension of ORMLite to target Android.
What I want to do 
I want to reproduce one of the behavior that Doctrine and Symfony are achieving in PHP with models.
In a word: 

From a yml file generate a bunch of BaseModel class with accessors
and things that won't change.
Let the real model inherits from this
BaseModel so that the user changes could persist even if they regenerate the models from the yml.

My question
I was wondering if this is good in practice to try to achieve such an objective on Android or if this will be risky in terms of performance (the heavy usage of inheritance).
If you think that it is clumsy, how can I allow the user to change the .yml file, generate the model and do no start from scratch rebuilding the customized aspects of his model.
I know this can be done by some "trick" but I really would like not to reinvent the wheel.
EDIT
Sorry, I forgot to add: I am using python to do this.
Thanks