Both are sons of professional men, both went to distinguished Hawaii private schools and both are lawyers.

But that’s about where the similarities end for Honolulu Mayor Kirk Caldwell and former U.S. Rep. Charles Djou, the man trying to oust him from Honolulu Hale’s third-floor corner office in Tuesday’s general election.

The 46-year-old Djou first won elected office to the state House of Representatives, representing his Kaneohe neighborhood, in 2000. He was just 30 and had spent several years as a practicing private attorney.

Caldwell, 64, also won his first elected seat in the state House. But when he won the right to represent Manoa in 2002, Caldwell was 50 and he had already spent more than two decades practicing law.

The Honolulu Star-Advertiser recently chatted with both candidates, and some of the people closest to them, to explore what makes each tick and how their personal backgrounds and life experiences led to this juncture.

At Punahou School, Charles Djou’s social studies teacher told his 11th-grade students to get involved in an election campaign. Djou chose to help veteran Republican Pat Saiki in her successful 1986 bid for Congress.

His primary job was to lick stamps for mailers, he said. Saiki wound up becoming a lifelong mentor, and it was she who first persuaded him to seek public office, Djou said.

In 2010, following stints in the state House and the City Council, Djou became the first Republican since Saiki to serve Hawaii in Congress.

Djou said he decided to join this year’s mayor’s race because he’s worried that his three children, who range in age from 9 to 23, won’t be able to afford to buy a home here.

“I am very troubled and concerned that our … community is increasingly moving in the direction of being something only for the well-off and the well-connected, and that’s wrong,” Djou said.

Because of his parents’ immigrant backgrounds, he said, he feels he connects with the middle class.

Sue Djou, an ethnic Chinese from Bangkok, and S.K. Djou, originally from Shanghai, both came to the U.S. to attend college. They met in Los Angeles, where they got married and Charles was born. The family moved to Hawaii when Charles was 3, after S.K.’s employer sent the engineer to the 50th state.

“A core part of my identity is that I’m a child of immigrants,” Djou said. “Both of my parents immigrated to the United States with very little, and I learned the values of hard work and integrity from my parents.”

Attorney Jonathan Lai, who has known Djou since the seventh grade and attended the University of Southern California Gould School of Law with him, recalls that both Charles and his younger brother Dennis attended classes neatly attired in polo shirts at a time when other Punahou kids typically wore T-shirts. Lai said the Djou boys’ parents likely wanted them to present themselves properly for their teachers.

When his friend entered politics, Lai said he wasn’t surprised.

“He’s always had an interest in helping the greater good, in helping the community,” said Lai, now a partner with Honolulu law firm Watanabe Ing LLP. “From very early on, Charles has been very sincere with his desire to help the state of Hawaii and not just focus on money or material wealth.”

Lai, who is pro-life, recalled having spirited but respectful debates in class with Djou, who is pro-choice.

Djou has served in the Army Reserve since 2001, including a tour in Afghanistan in 2011-12 with the 10th Mountain Division. He holds the rank of major.

Djou has gone from state House member to Council member and then congressional member in a span of 16 years, leading skeptics to say he is an opportunist always waiting for the next elected job to come along. They note that he waited until the day before the June registration deadline to announce his plans to run for mayor.

But Stacey Djou, the candidate’s wife, said the mayoral run was not something that came on a whim but a decision that the family, as a whole, took time to think about and agree upon.

“We were planning on sitting out, Charles was planning on sitting out,” Stacey Djou said. “We’ve been through so many tough campaigns and he, I think, really wanted to spare our family.”

But “story after story” about the now-$8 billion rail project and the growing number of homeless on the island got them all thinking, she said.

If she or any of the children had said no, Charles Djou would not be a candidate today, she said. “Our children get that it’s important to be part of the solution.”

When not working or campaigning, Djou’s main outlet is spending time with his family — Stacey, an adult son and two school-age daughters. He likes to take one daughter surfing, the other to piano lessons.

“And then we get to go to McDonald’s afterward,” said the mayoral candidate about one his of his professed weaknesses.

Oahu Sugar Plantation doctor Paul Caldwell and his wife, Jeanne, moved their family to Hilo from Waipahu when Kirk, their eldest son, was 5.

The mayor’s sisters — Candy Luscomb of Kailua, Cindy Cavano of Massachusetts and Kimberlee Saunders of Australia — recalled fondly how their big brother was both a nurturer and an instigator — as the kids went fishing, swimming or camping.

“If we were going to go do something, Kirk would go, ‘Come on! Come on! Let’s go do this! Let’s get everybody together!’” Luscomb said. “‘We’re all going to go build a fort by the guava tree!’”

The late Jeanne Caldwell, a nurse until she became a stay-at-home mom, instilled in the children the need to respect people, care about them and help them whenever possible, Luscomb said. “She would stand up for anybody she felt deserved help … and I think Kirk is much that way. It doesn’t matter who you are or what you do, he’ll stand up for you.”

When Kirk would return home on weekends from Waimea’s Hawaii Preparatory Academy, where he boarded during the week, he often brought friends who had nowhere else to go.

Saunders said whenever they did something outdoors, it was Kirk who would make sure that everyone helped out cleaning the area afterward, another lesson from their mother. “My mom always said that you leave a place better than when you found it,” she said. “You never leave someplace without trying to make some sort of improvement, and I think Kirk is that way, very much so.”

All the Caldwell children, including youngest brother Keith of Hilo, have made community service a priority, the sisters said. “You don’t want to just exist, you want to make things better, and I think Kirk is like that,” Luscomb said.

The mayor said solving problems is what drew him to both law and politics.

His first taste of politics came while attending Tufts University just outside Boston. Caldwell volunteered with Democratic South Dakota Sen. George McGovern’s failed 1972 presidential bid against Richard Nixon. Caldwell said he learned about the civil rights movement as a kid watching television with his dad in the 1960s and believes that laid the foundation for him to become a Democrat.

“They seemed a little bit more wanting to change things (to) a more fair and equal society,” he said.

It’s also what led him to work with the late U.S. Sen. Daniel K. Inouye in Washington, D.C., where he met his wife, bank executive Donna Tanoue. Still, it wasn’t until then-President Bill Clinton appointed Tanoue chairwoman of the Federal Deposit Insurance Corp. that Caldwell considered running for political office himself.

He had formed a successful law practice and recognized he was good with people, and running for public office was “the next part of the journey,” he said. Tanoue agreed to support him.

And when the couple and their school-age daughter, Maya, returned to Hawaii, they moved to Manoa, where he ran successfully for the state House seat vacated by Ed Case. Once in the House, he rose quickly up the ranks of the Democratic caucus and became majority leader.

But Caldwell said he was frustrated because many of the issues he wanted to tackle — such as housing and roads — were city issues. That’s what attracted him to Honolulu Hale and led to his decision to accept then-Mayor Mufi Hannemann’s appointment to be his managing director.

While Caldwell’s four years as mayor have been largely defined by his efforts to wrestle the escalating rail project and the island’s homelessness situation, the mayor also likes to remind people that his administration has prioritized infrastructure needs from road repaving to sewer system upgrades.

Like Djou, Caldwell enjoys spending time with his family, especially outdoors. One pastime is taking his sister Candy, who is paralyzed below her waist, out swimming.

When he has free time alone, Caldwell said he likes working on his yard where he has built two koi ponds and rock walls. Not only is it therapeutic, he said, “it’s me telling me what to do — no one else telling me what to do.”