McCoy's back story

[Rat Boy]

But, I do hope that McCoy's back story [...] don't quite change. He's too good a man for total revision.

But then again, what do we really know about his backstory?

He has the hands of a surgeon, allegedly.

 

[THE CHEBB]

i think some of it was with character guidelines developed for the characters back when the series was on the air.
bones' daughter was originally supposed to have been in the space hippies episode.

I reach

 

[The Wormhole]

I believe it was originally DC Fontana's intention that McCoy was to have had a son, but this was changed to daughter at DeForrest Kelley's request.

 

[FemurBone]

I've been saying all along that starfleet was a second career for McCoy. He had been working as a civilian doctor for many years before becoming a starfleet officer.