My husband's Aunt Lilly runs a delicatessen that's been in business in suburban New York for almost 93 years. Lilly, a former opera singer (think Marguerite in Faust), has been preparing her special German potato salad and charming customers since she retired from the stage, in 1958, and though she's now in her mid-80s, she is determined to live long enough to see this small store her parents once owned reach its centennial. No one in the family doubts that Lilly will prevail. She is propelled by a feisty spirit and a fierce family pride.

As readers of Inc. know, this magazine is interested in every kind of privately held company: the fast grower, the business on the verge of ruin, the enterprise that will change the way we entertain ourselves or pay our bills or educate our kids. This month we decided to turn our attention to multigeneration family businesses.

Why do these companies not only survive but thrive? Is it a matter of economic philosophy? Business acumen? Fiscal responsibility? Something like a success gene, woven into the DNA of some families but not others? With these questions in mind, contributing writer Adam Bluestein interviewed the current heads of half a dozen fifth- and sixth-generation family businesses, including the oldest cigar shop in Chicago and a billion-dollar Omaha real estate concern. Their insights on business and longevity are smart and thoughtful and, I think, useful to anyone who is running a company. I think I'll even send the story to Aunt Lilly.