Millennials aren't buying homes like their parents and grandparents did. That's largely because it's harder to afford a house these days: high real estate prices, stagnant wages and student loans hold young people back.

And a good chunk of those who have been able to purchase a home haven't done so on their own. New data from financial services company Legal & General finds that 43 percent of homeowners age 34 and younger got money from family or friends.

Likewise, just over half of prospective homeowners 34 and under expect to benefit from financial assistance when they do take the plunge, L&G finds.

"House price growth in the U.S. has outstripped wage growth in 2018, meaning that on average across the U.S.A., houses are becoming more unaffordable," the survey says. "This suggests the need for assistance [from family or friends] with a home purchase is on the rise."

One reason so many millennials aren't able to afford homes is because of the rising cost of college. Between 1988 and 2018, the average price of tuition at a public four-year institution rose by more than 200 percent.

The L&G survey found that 35 percent of college graduates who are carrying debt and don't already own say their student loans have made it "much more difficult" to save up to buy a home.

As a result, "many millennials have effectively given up on owning their own home — at least in the near term," the survey says. "Of those under 35 who don't already own, 43 percent say they don't expect that to change in the next five years — most often (40 percent) because it's simply not feasible to save for a down payment in that time frame."

It would take a lot to put together a sizable down payment in half a decade. To save up enough in five years to put 20 percent down on a $275,000 house, which is the cost of the median home in the U.S., you'd need to save around $800 a month with a 5 percent return on investment.

Currently, millennials have a median amount of just $2,430 saved.

And a down payment is just the beginning. You'll need more money to account for closing costs, insurance and other fees. Home prices vary, too, and it's possible that the median price will rise in the next five or more years.