Why disability?

It seems to me that nobody has a good answer to the question, "Why does disability exist?" The best answer I've heard so far is my son's, which was: "It's just a series of coincidences, a set of circumstances that allowed it to happen." In fact, many people, both Christian and non-Christian have been utterly stumped by the question. Some have provided answers, but answers that don't seem to me to hang together.

If we have suffering and evil in the world because of our ancestors' sin, (a Christian answer), why does it hit some people and not others?

If we are in fact all perfect, according to our form and function, which is to ensure the survival of our species, (an atheist answer) then why do some people have severely imperfect minds or bodies, which limit their quality of life? If life is just about ensuring the survival of humankind, does that mean that I am of no further use, being past childbearing age?

Another atheist answer, (my son's again) is that we can strive for nobility, remembering what he considers a really helpful guideline, which is, "Do to others as you would like them to do to you." He didn't know, or had forgotten, that this was Jesus' command.

What would Jesus say about disability? One (Christian) parent replied that seeing each one of her children as created perfect in the way they are has enabled her to benefit so much from having one child with special needs. "If I can somehow see people with a disability with God's eyes - to see the pearls in the oysters - and to see how precious we all are, as we are, this is God's purpose."

"Why me?" I'm sure that's the question of every person enduring ongoing pain and disability. The only answer I've ever come up with is "Why not you?" I hasten to add, it was the answer God seemed to give to me, when I asked him the question. It's not an answer I've imposed on suffering people!

If we read Chapter 9 of the Gospel of John, and indeed any or all of the Gospels, Jesus seems to see illness, suffering and disability as an opportunity to display God's love, by showing compassion, and bringing healing. I think this can make ongoing suffering even harder for Christians. If Jesus would be like that when he lived with us in the flesh of a human being, why isn't he still like that now, when he lives in us through his Spirit?

Dear Father, what are you up to?