Nearly half of the men and women serving in Congress are millionaires. This term's freshman class is especially wealthy, with an average net worth that was $1 million more than that of the average American household.

Indeed, the last person on The Hill's list of the 50 wealthiest lawmakers in Congress is Rep. Mike Kelly (R-Pa.), who trails his wealthier colleagues with a paltry $6.5 million in the bank.

Few people in America become millionaires without significant business or real estate investments, and this group is no different. But where did they make the money to invest in stocks and vast tracts of land in the first place? Here are a few ways today's lawmakers became very, very rich.

Being born with money
Yes, Sen. Jay Rockefeller IV (D-W.Va.) is part of that Rockefeller family. The great-grandson of famous oil tycoon John D. Rockefeller, the five-term senator is worth $83.8 million.

Of course, no list of wealthy politicians would be complete without a Kennedy. Among his many assets, Rep. Joe Kennedy (D-Mass.) lists multiple trust funds, just another advantage of being a member of one America's longest-running political dynasties.

Then there is Rep. Fred Upton (R-Mich.), an heir to the Whirlpool fortune, who is worth $8 million. In case you were wondering, his niece is superstar swimsuit model Kate Upton.

Marrying rich
Several members of Congress simply married their way into wealth. Sen. Richard Blumenthal (D-Conn.), a former attorney general, tied the knot with the daughter of a New York real estate magnate. His net worth? $76.6 million.

Other members of Congress who took very lucrative vows on their wedding day: Democrats Rep. Scott Peters ($44.7 million) and Sen. Dianne Feinstein ($41.6 million) of California; Rep. Chellie Pingree (D-Maine), who is worth $31.5 million; and Sen. Claire McCaskill (D-Mo.), whose husband's investments make up a good portion of her $14.9 million net worth.

Riding the tech boom
One day, we'll be saluting President Zuckerberg. Until then, we have plenty of tech millionaires working in Washington, including Rep. Jared Polis (D-Colo.), one of the founders of His fortune is valued at $60.2 million.

His colleague, Rep. Suzan DelBene (D-Wash.), made part of her $23.9 million working for Microsoft for 12 years alongside her husband, Kurt.

Sen. Mark Warner (D-Va.) was one of the co-founders of Nextel, which was eventually bought out by Sprint. He is also a big investor in new tech start-ups, which have helped him acquire a fortune of $88.5 million.

Making money off cars
Meet the richest man in Congress: Rep. Darrell Issa (R-Calif.), worth a cool $355.4 million. Before he was attacking President Obama over Benghazi, he was founder of Directed Electronics, which developed the popular Viper car alarm.

Car dealers and politicians are trusted by the public in equal measures, which doesn't bode well for Rep. John Campbell (R-Calif.), who owes much of his $9.4 million to five California car dealerships. Rep. Scott Rigell (R-Va.) also owns a car dealership, which is worth around $5 million.

Throwing money at questionable ideas
Ever use pepper spray that was disguised as a pager? You have Rep. Trent Franks (R-Ariz.) to thank for that. Franks has $100,000 in patent holdings for a product called the LP 1000 Life Pager. (Most of his $11.1 million is invested in more conventional assets).

Meanwhile, the husband of Rep. Nancy Pelosi (D-Calif.) invested $5 million in two football teams. Sadly, they belonged the United Football League, which tanked in 2012.

Read The Hill's entire list of the 50 wealthiest members of Congress here.