(Bloomberg News) Less than half of wealthy Americans say that leaving an inheritance is important, according to a survey by U.S. Trust.

"I think it's reflective of the mindset of a lot of the baby-boomer generation," said Keith Banks, president of U.S. Trust, the New York-based private wealth management unit of Bank of America Corp., the largest U.S. lender by assets. "I think they expect to live a lot longer and I think their first concern is, 'Am I enjoying the hard-earned wealth I created?'"

Of the 457 individuals surveyed, each of whom said they had $3 million or more in investable assets, about 49% said that passing assets on to heirs is very important to them. That may help explain why about half of respondents said they've never spelled out how they'd like their estates to be divided among heirs, said spokeswoman Lauren Sambrotto for Charlotte, N.C.-based Bank of America. U.S. Trust clients generally have at least $3 million in investable assets.

About 67% of those surveyed haven't told their children the full extent of their net worth, and 15% told their children nothing about their family's wealth. The average age of those surveyed was 61.

"There's a concern that if the kids are fully cognizant it may start to influence how hard they work at their own careers," said Banks.

About 78% of those surveyed said their children won't be mature enough to handle their inheritances until they are at least 30 years old, and 45% said their children won't be mature enough until they are 35 or older.

Protecting Children

U.S. Trust hired Rhinebeck, New York-based Phoenix Marketing International to survey the individuals online in January and February.

The last time U.S. Trust conducted a survey on attitudes about personal wealth and estate planning was in 2007, almost a year before the collapse of Bear Stearns Cos. About 43% of respondents then said they owed it to their children to leave a significant inheritance, and the average age at which participants said their children assumed responsibility for their own money was 27.

"If you knew you had a tremendous amount of wealth behind you, would you be as ambitious, would you be as self-reliant, knowing that?" said Doug Ketterer, head of New York-based Morgan Stanley's U.S. private wealth management unit, where clients have $20 million or more in assets. "In their own way they're protecting their children to make sure they can live the life they hope they would live."