Why did young Charlie inherit all that money and why did he have to be taken away from his parents? They were apparently poor people, so that seemed not logical at all. It was also strange for me that his parents could not go with him to take care of him. Ok, his father was apparently abusive, so the mother wanted to get her son as far away as possible, but why couldn't she go?
His mom runs a boarding house, and one of her boarders went broke and couldn't pay the boarding fee. As compensation, the boarder gave her the deed to a supposedly worthless, abandoned mine shaft. Years later, the mine became valuable and the Kanes became rich.
His mother clearly wants to separate her son from the father. So either she goes with her son and leaves the husband behind (which she may not want to do), or she lets her son go alone and makes sure he will be well taken care of. She obviously thinks that the latter is the lesser of the evil, and she can always visit the son once in a while.
It wasn't uncommon for people to send their children away to 'improve' them. Boarding schools, indentured servitude, an east coast education...it was all meant to provide a brighter future for the child.
Perhaps, if Mrs. Kane went with Charlie, Mr. Kane would have grounds for divorce (abandonment) and would be entitled to part of the fortune as settlement.
Inclined to guess that both parents died not long afterwards. Thatcher was not a bad man - did his best and I believe genuinely liked Charlie - but not suited to. bringing up children
I think its just some euphemism for: Citizen's parents (Mr. and Mrs. Kane) sold him to a uhh not-so-morally-well-aligned gentleman with a very special interest in young boys. As a consequence he's later angry and fucks up his marriage and grows the stache.