Deafness is generally treated and regarded as a disability, but could it be reasonable to regard it more like an ethnicity? That will probably sound intuitively false to most people, but there are a number of aspects of deaf "culture" which are surprisingly close to what we usually think of as being central to ethnicity. Even if deafness isn't really an ethnicity, it might be useful to think of it in those terms sometimes.
Editors Harlan Lane, Richard C. Pillard, and Ulf Hedberg write in the book The People of the Eye: Deaf Ethnicity and Ancestry:
ASL signers have been contending for nearly a half century that they are a linguistic and cultural minority, and there is extensive scholarship to support that view. Are they also an ethnic group? Deaf and hearing scholars have raised the issue from time to time over several decades; an inventory of early use of the concept of Deaf ethnicity is in the endnotes. This book is, however, the first extended examination of ethnicity and the DeafWorld.
Language is a means of communication but it is also the purveyor of culture, including traditions, rituals, norms, values, and the language arts. Language, handed down across the generations, provides continuity with the past. It is a symbol of ethnicity and identity, and a force for social cohesion.
There is no more authentic expression of an ethnic group than its language. To disparage that language disparages the people who speak it and praising their language praises them. When an ethnic group demands more equitable treatment for their language (for example, its use in the media and in schools), they are also seeking more equitable treatment for their group and their culture.' ASL signers hold very dear the communicative, cultural and emblematic functions of their language.
Members of ethnic groups commonly have strong emotional ties to their kind. Loyalty to their ethnic group may even at times lead them to act against their own personal interests. What are the wellsprings of such commitment, which is exceeded only by family loyalty?
Honestly, I'm not inclined to agree with the conclusions and position of Harlan Lane, Richard C. Pillard, and Ulf Hedberg. They have an interesting point to make, but I don't see why ASL should be regarded as significantly different from the many variations on English that exist in America — and not all those variations are treated as central to any sort of ethnicity. Applying the concept to deaf ASL users may have interesting uses, but I don't see it as a justified form of categorization here.