Essays / How to compare and contrast myself and another member of my family? [9]

Hi, This is my first post.
I'm writing this to ask you guys about the compare and contrast essay.
I have to compare and contrast myself and another member of my family.
And as long as i know how to write it, I have to find "the purpose" of writing this essay.
But I can't think any purpose :( It could sound silly but yes, it is!.
The subjects being compared and contrasted would be my mother and me.
Before writing the introduction, I divided the points in to 3 such as physical features, mindset(in buying and cleaning) and eating habit(like and dislike, that kind of thing).

DO you think those points are good, fine? or not goo?
What can be the purpose?
Please help me!