The former Two and a Half Men star has dominated the news over the last few months with his bad behaviour, which has included trashing a suite at a New York hotel, rehab, hospitalisations and a public feud with TV bosses which eventually cost him his job.
His famous father Martin, who also battled addiction in his youth, is adamant he can understand the "hell" his son is going through, and insists Charlie's struggle with booze and drugs has left him child-like and unable to control his emotions.
He tells Britain's Telegraph magazine, "Charlie's 45 years old. He's not a kid. Emotionally he still is. Because when you're addicted, you don't grow emotionally. So when you get clean and sober you're starting at the moment you started using drugs and alcohol. You're emotionally crippled...
"I know what hell he's living in. I've had psychotic episodes in public. One of them was on camera - the opening scene of Apocalypse Now. So I know what Charlie is going through. And when you do something like that, that is out of control, that's the most difficult thing. You have to have courage."
And Charlie Sheen's elder brother, Emilio Estevez, insists the actor's meltdowns may indicate he inherited their father's self-destructive tendencies because all four children in the family had the same upbringing.
He adds, "We all had the same set of rules. So it really gives credence to this theory that it is genetic, and that sometimes it skips either a generation or siblings. My mother doesn't drink. My other brother hasn't had a drink in over 10 years, my dad hasn't had a drink in 20. And I make wine."