does income affect disability?

I’m taking an online class called “career development” that teaches teachers about the importance of giving students with disabilities a chance at gainful lifetime employment.  Here’s the stunning statistic I found in the first week of readings: 8% of Asian adults report having disabilities, as compared to 17% of Hispanics.  The article didn’t have any comment about the coincidence of poverty and disability, but I can’t help but think that this is the reason for this divergence among the races.  What could be the cause(s)?  Nutrition?  Toxins in the environment?  Parents’ level of literacy?  Exposure to vocabulary as toddlers?  I’d love to know!  Whatever the reason, I can’t believe it would be due to genetics, and therefore we must be able to do something about it.  I’ve got to believe that many disabilities can be prevented, maybe half, if we are to believe that Asians have the same genetic disposition that Hispanics have.