I get what you're saying - not every kid is going to do everything their parents do.  Kids get older and figure out what they're into, and it's not always the same stuff as their folks. 

But if little Joey sees Mom or Dad spending all weekend at the casino or racetrack every week, he might start thinking gambling is no big deal.  And that could lead to him developing some unhealthy gambling habits of his own down the line, even if he doesnt get full-on addicted.

Now sure there are probably some decent things kids can pick up from parents who gamble too - learning about risks or setting limits with money and stuff. 

Bottom line though, the best way for parents to keep their children from ending up with bad gambling behaviors is to be straight with them about what gambling is and why it matters to do it responsibly.