Ask your father-in-law. Ask him if he honestly believes that having the Italian flag on his business card does not influence a potential Italian customer in any way.

Ask him if he also has the Italian flag in his phone book ad, or, if he doesn't have an ad, if he would put it there if he were to buy one? And if the answer is yes, ask him this:

"Let's say an Italian person was looking through the phone book, and he saw several competing businesses. Do you think that seeing the Italian flag might make them more likely to choose your business over its competitors?"

I will concede that it's possible the thought never occurred to him, and that the accusations I've leveled here are baseless in his case at least. But I'd be very curious to know his answer to those questions.

Please note: All of the above is null and void if his business is an Italian restaurant.

Also note that I'm Italian, too, and I would not be influenced one way or the other by an Italian flag on a business card or a phone book ad.