Having grown up with persons who have differing abilities (disabilities) and have family (including children) with disabilities 'today', I have never treated such persons differently than to how I like to be treated myself.
The only time I would behave differently to an individual with a disability is when accommodations for their challenges or different ways of needing to do something is apparent.
A disability doesn't define the person, in my mind or change how we should view them as a fellow human being. We are all human, though consideration for our differences may be needed sometimes.
Cheers, Louise :)