[ocimbote]

Out of curiosity, is there any source to endorse that?

I mean, it certainly takes a MJ to get to this level without music theory, but if the fact is confirmed... wow! (Tried to phrase it properly but "wow" conveys best that I'm speechless)

[mkl]

There are lots. Here's one: https://www.nme.com/blogs/nme-blogs/the-incredible-way-micha...

[Lewton]

"without music theory"

Reading sheet music is not music theory

[lo_zamoyski]

Also, historically, most people who made music probably never read music. I'm thinking of everyone from troubadours to traveling musicians to that great uncle who plays the mandolin or grandfather who plays the fiddle or the aunt who sings in the local church choir. It was all learned by ear from others, memorized, and improvised. Indeed, historically, improvisation was what characterized the musician and musicianship, not the ability to read music. That is a recent development.

If Michael Jackson indeed never learned to read music, then it would seem he is rather representative of the historical case rather than an exception. He grew up in a musical family and so he was always in an environment that constantly exercised the faculties involved. And we're talking popular music, after all, not some complicated orchestral work or composition.