Look closer and you will see that there are far more cases of
Ranma punting Happosai or his father compared to Akane punting Ranma.

I never tried to count them.  But Happosai and Genma _actually deserve it_.
Ranma doesn't go around misunderstanding them and then hitting them based on
the misunderstandings.  Also, they're people perfectly willing to fight _him_,
so he's interacting on their own terms, rather than beating a helpless victim.