Most big family fortunes vanish within a couple of generations, which is bad news for anyone assuming their money will outlive them.

• Building wealth changes shape at each level, and the rules that got you to $100,000 stop working once the numbers get big.
• The Medici family is the rare case that held on to its money for seven generations.
• The Rockefellers are still holding wealth three or four generations in, but that is the exception, not the rule.
• The Vanderbilt fortune barely lasted a generation or two because the father never taught his children the habits that built it.
• Passing on money without passing on discipline is what kills family fortunes.

Outlook: Families that focus on teaching habits rather than just handing over assets are the ones likely to keep their money intact.