Addicts lie. All the time. They think they have to in order to keep up their double life.

Once you know that someone is an addict (and not in recovery), your best bet is to just assume that whatever they say is a lie. Because it most likely is. That's sad, but it's just one of the side effects of the disease (also one of the contributors to it).

And if the statement originated with his dad, then there is a somewhat better chance that it is true. But if his dad is still in an enabling mode, then his dad has to lie almost as much as Sark does to maintain the cover (whether he realizes that is what he is doing or not).

I don't know any details about Sark's situation, but addiction follows well-worn, all-too-familiar patterns. Once you've seen it a few times, it isn't hard to recognize.