How young millionaires made their money

There are plenty of young millionaires out there, but a recent study suggests that many of them had a head start, as nearly half grew up wealthy.

The "Insights on Wealth and Worth Survey," published last month by the U.S. Trust, found that 45 percent of millennial respondents (defined as ages 18 to 35), grew up wealthy.

That compares with only 28 percent of Gen-X millionaires and just 18 percent of baby boomer millionaires.

Millennial millionaires aren't all living off their trust funds, of course. And for many, their age hasn't allowed them as much time as older generations to build their own wealth.

When asked how their wealth was accumulated, the millennials surveyed said about half came from "earned income." That was roughly in line with Gen X and boomers.

Yet 20 percent of millennials' wealth came from inheritance, compared with only 10 percent for Gen Xers and 8 percent for baby boomers. Those generations were more likely to supplement their income through investments.

Those millennials who did inherit money inherited a lot. Thirteen percent said that at least half of their wealth was inherited, versus 5 percent for the other generations.

Growing up with all that money has made these millennials less focused on frugality than other generations. When asked which family values were stressed when they were growing up, only 39 percent of millennial millionaires said "financial discipline."

That compares with 60 percent of Gen Xers and 75 percent of boomers.

They were less likely to attribute their success to "hard work or practice" than other generations, and far more likely to credit "connections" or "a mentor."

"Millennials are less likely to have had academic achievements and financial discipline strongly encouraged than baby boomers and older respondents," the report said.

But don't call them "spoiled" just yet. The millennials surveyed started working for money at the average age of 14, compared with an average of 16 for Gen Xers and 15 for boomers.

They started investing in stocks at an average age of 22, compared with 24 for Gen Xers and 25 for boomers. However, that's likely because the millennials started out with more money early on.

Millennial millionaires were raised with more charitable and civic responsibility than other generations, as well.

Thirty-two percent said charitable giving was stressed in their family as they grew up, compared with 27 percent of baby boomers. And 30 percent said civic responsibility was stressed growing up, compared with 29 percent of boomers.

The "Insights" survey polled 684 people in the U.S. with investible assets of more than $3 million.

Of the respondents, 13 percent were millennials, 24 percent were Gen Xers, and 42 percent were baby boomers. The remaining 21 percent were ages 72 and older.