Donald Trump had a contentious relationship with his older brother

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Donald Trump wasn't always the heir apparent to his father's real estate business.

He was the fourth of five children born to Fred and Maryanne Trump.

He grew up with his three older siblings Maryanne, Fred Jr., and Elizabeth, as well as his younger brother Robert.

Fred Trump Sr. initially viewed his namesake as his potential successor, but Fred Jr. was more interested in pursuing a career in aviation.

The current president and his father reportedly took a low view of his career choice. Trump told The New York Times tha the would confront his brother about his choice of occupation, saying "I was too young; I didn't realize. Now I give speeches on success, and I tell people, 'You've got to love what you're doing.'"

Fred Jr. became an alcoholic and died at the age of 42.

Meanwhile, Trump's oldest sister Maryanne also achieved a successful career in the realm of government — although she made her mark in the judicial, not executive, branch.

Maryanne was a district judge in New Jersey, and also served on the Third Circuit's Court of Appeals before retiring in 2011. According to The New York Times, she is close with Donald, who said of her: "She feels that women are very smart and can be very tough and can be at least equal to men, and that women can fight very hard."

The New York Times also reported that Trump's lawyer and ally Roy Cohn may have advocated for the Reagan administration "to put his sister on the bench."

According to the IB Times, Trump's other sister Elizabeth worked as an executive at Chase. Like Maraynne, she and the baby of the family, Robert, keep a lower profile than their brother. Robert worked for the family's real estate business as an executive, and told Page Six that he thought his older brother was doing "a great job" as president.