How did The Addams family get so rich?

I watch The Addams family on foxtel.. it's one of my most favourite shows.. I'm just wondering if anyone knows just how they got sooo rich?? their house is mive!!! and they have expensive stuff.. plus Gomez gives away his money so easily and in big amounts.. like giving $100,000 to the new zoo commissioner when he first met them :O .. i know they mentioned once that they have diamond mines... and a swamp and they have money in stocks.. they're like... billionares!