All great athletes are dual-sided.

That is, they must be two vastly different people, depending on where they are.

On the ice, the field, the course, the court, or in the water or air, they are trained to be aggressive — they love being aggressive —taking what they want.

Out of the arena, the competition, they must be social, restrained, law-abiding.

If I told you of all the times NFL players have told me they loved football because ‘‘I’d get arrested if I did this off the field,’’ you’d be amazed.

Or maybe not. Because we want and expect our football stars to be barely controlled savages. Same, in essence, with all sports.

The problem for the athletes is turning it off.

Patrick Kane is a normal-sized, skillful player on the ice, not a brutish man who runs guys into the boards. But he is as aggressive and arrogant and self-centered as any bruiser anywhere.

So how does this factor into the ongoing mess in Buffalo, where Kane is the subject of a police investigation involving a woman? As yet charged with nothing, Kane nevertheless has stepped into the dark hole that awaits all stars who forget that the game of life is nothing like the games they play.

I believe Kane’s problems stem from a few obvious issues.

First is that two-sided thing. I don’t think he has learned much at all about leaving his hockey personality in the locker room.

Second, we don’t know if alcohol was involved in this situation, but in the past, the things that have infuriated Blackhawks management the most have involved Kane and drinking. Asked a while back if he thought he had a drinking problem, Kane replied, ‘‘I don’t think so.’’

Not a strong reply. Nor does it matter what he thinks. The proof’s in the pudding. Have any of Kane’s off-ice issues occurred when he hadn’t been drinking?

We all know the effects of alcohol. It’s not like marijuana, where the politically correct and politically active will say they’ve smelled it but know nothing about what it does.

Most adults have been drunk at some point, and they are aware of how alcohol can make them act. I sure know. One time, years ago, I ended up in a drunken brawl with pals on New Year’s Eve at a Greek restaurant on Lawrence Avenue.

The dumbest part, besides being stupid drunk? I was wearing a tie, and a guy tried to strangle me with it.

At any rate, I will never pretend that alcohol isn’t one of strongest legal drugs in the world. It is every adult’s burden to deal with.

About 10 years ago, when I went to a traffic safety course after getting a speeding ticket, I took the final test, and I well remember a multiple-choice question that said, ‘‘What is the first thing to be impaired after drinking?’’ The choices were hearing, speaking, balance, etc.

But the correct answer was judgment.

And there you go.

Kane’s judgment may be his undoing. He may a candidate for alcohol rehab, who knows?

But this developing incident in his home area adjacent to Lake Erie may be nothing, or it may be his undoing.

Hawks president John McDonough is out of his mind with anger and disgust over this last Kane incident during the offseason. McDonough came in and helped engineer the Hawks into perhaps the most successful and envied franchise in all of pro sports. It would not be wrong to call him, as one would call most great executives, a control freak. He wants the message controlled so that his product is the best any fan could want: a wildly successful, family-friendly, hugely entertaining and scandal-free franchise that does nothing wrong.

If the time is right and the disgust goes unabated, McDonough will dump Kane from the organization like a rotten timber from a mansion.

I spoke earlier of Kane’s issues, and here, I believe, is the third: He is Peter Pan. He has never had to grow up.

This is because he was identified as a hockey genius when he was just a child, and so much smoke has been blown up his behind that he might reasonably be expected to lift off the ground like a hot-air balloon.

He never went to college. He never truly matured. He never was able to shed the hockey culture of excess that has ruled for generations.

This is terrible for the Hawks. Of course, it is terrible for the woman involved — if, in fact, this situation is real and true. And for Kane, it’s do or die.

The clock ticks.

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@RickTelander

Email: rtelander@suntimes.com