Donald Trump's firstborn, Donald Trump Jr., has referred to his father as his mentor and best friend.

Born in 1977 in Manhattan, Donald Jr. is one of three children of Donald Sr. and his first wife, Ivana. He was only 12 years old when his parents separated and he and his siblings lived with their mother after the divorce. But Donald Jr. still built a strong relationship with his father and has followed partially in the Republican nominee's footsteps, taking a major role in the family company. He hasn't yet run for office, but the idea has crossed his mind, he says.

Scroll down for more about the eldest child of President Trump.

He has taken over the family company

Donald Trump Jr. (center), along with Eric Trump,

Donald Trump Jr. (center), along with Eric Trump, will run The Trump Organization, Donald Trump's real estate business, now that his father is president. Donald Jr. previously served as an executive vice president of the family company, overseeing new projects and development of the company's real estate, hotels, golf courses and more.

(Credit: AFP / Getty Images / Oli Scarff)

He's married and has five children

Donald Jr. married Vanessa Haydon, a former model,
Donald Jr. married Vanessa Haydon, a former model, in 2005. They had been introduced at a fashion show in 2003 by Donald Trump Sr., according to a New York Times article. The two now have five children, Kai, Chloe, Donald, Tristan and Spencer. (Credit: Getty Images / Chris Kleponis)

He speaks Czech

Donald Jr. learned how to speak Czech after
Donald Jr. learned how to speak Czech after visiting his mother's parents in a town outside of Prague. According to a New York magazine profile, Donald Jr. was very close with his maternal grandparents, Milos and Maria Zelnicek. He often went fishing, boating and hunting with his grandfather. (Credit: Getty Images / Grant Lamos IV)

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He attended The Wharton School

Donald Jr. followed in his father's footsteps by
Donald Jr. followed in his father's footsteps by attending the Wharton School of the University of Pennsylvania. He had previously attended The Hill School, a boarding school in Pottstown, Pennsylvania. (Credit: Getty Images / John Moore)

Controversial 'gas chamber' remark

Trump's first son was criticized after he said
Trump's first son was criticized after he said the media would "be warming up the gas chamber right now" if Republicans were acting the way Democrats were during an interview on Sept. 15, 2016. The Anti-Defamation League called on him to retract the statement and said, "Trivialization of the Holocaust and gas chambers is NEVER OK." Donald Jr. later said he was referring to capital punishment, not the Nazi-led Holocaust, when he made the remark. According to the Death Penalty Information Center, only 11 executions in the United States have been done by gas chamber since 1976. (Credit: Getty Images / Chip Somodevilla)

He wants to run for NYC mayor – maybe?

Donald Jr. didn't rule out the idea of
Donald Jr. didn't rule out the idea of running for mayor of New York City during an interview on CNN in July. "I never like to rule anything out," he said. "As my father's always said ... we always like to keep our options open. So if I can do that as a service to our country, I'd love to do it." Donald Trump Sr., however, didn't seem to think his son would actually ever run. "I don't see that happening," he said on Fox News. (Credit: Getty Images / Chip Somodevilla)

He enjoys hunting

Donald Jr. (left) and his brother Eric both
Donald Jr. (left) and his brother Eric both enjoy hunting. They came under fire in 2012 when pictures emerged of them posing with the wild animals they killed in Zimbabwe, but the brothers said they were not hunting illegally or killing animals that were endangered. Donald Jr. defended hunting as a hobby in an interview with Forbes. "Hunting forces a person to endure, to master themselves, even to truly get to know the wild environment," he said. "Hunting and fishing makes you fall in love with the natural world." (Credit: Getty Images / Robyn Beck)