After 151 years in the oil industry, the Rockefellers have gone from monopolists to moralists.

The heirs of John D. Rockefeller, who put his family on the path to one of the greatest fortunes in history when he entered the oil refinery business in 1863, are divesting all their holdings in the industry, not because it is unprofitable but because they believe it to be immoral. In so doing, the Rockefellers are joining a small number of heirs who have turned their backs on the family business because it did not align with their conscience.

Patrick Reynolds, grandson of legendary tobacco baron R.J. Reynolds, divested himself of some $2.5 million in tobacco stocks in 1979, the only fortune he had. His reasoning was twofold, he said: He saw the effects of tobacco both on his father and on the developing world.

“My only memories of my father are of a man dying from smoking…[and] I wasn’t comfortable making money off a product that was killing people,” Reynolds told The Daily Beast. “They were preying on uneducated people in Third World countries. I could see that was wrong.”

His family members originally objected to his activism, arguing that it would force the company’s stock down. When Reynolds spoke out against the tobacco industry before a congressional hearing in 1986, it was the first time a figure with ties to the industry had spoken out publicly against it.

John Robbins, the heir apparent to the Baskin-Robbins fortune, went a step further and walked away from the family business entirely. Some of his family members also complained that his actions could affect the company’s stock price, and the bitterness lingers in the dessert dynasty today.

“I didn’t divest, I just walked away from all the money, period,” Robbins said. “I am just so convinced that junk food and high sugar food are undermining the health of people…It caused a lot of strain.”

The common thread among these heirs is the use of their family name to make a broader social critique—and the power that comes with turning against what your family is best known for. Robbins said the news of the Rockefeller philanthropic group’s divestment from fossil fuels was powerful mostly because of the name attached to it.

“The [Rockefeller] name carries a certain cachet because of Standard Oil,” he said. “Their name is almost synonymous with oil…that gets people’s attention, and for a good purpose.”

Reynolds acknowledged that much of his appeal comes from being the grandson of R.J. Reynolds. Like Robbins and the Rockefellers, speaking out against the source of family wealth becomes a source of authority.

“I’ve got a great platform as a Reynolds to make a difference on this issue,” he said. “That’s why I do this work.”

The Rockefellers aren’t divesting merely out of altruism. They believe that companies trafficking in fossil fuels will eventually face financial problems. But for Reynolds and Robbins, obeying their consciences came with a price tag.

Reynolds spent $1.5 million on an anti-smoking campaign, a large chunk of his wealth. He activism necessitated setting aside what he calls “a glamorous life before [he] spoke out against tobacco.” He is now “financially challenged,” he said, and focused mostly with anti-tobacco activism and speaking at schools and universities.

For Robbins, the price tag was even higher. He walked away from a fortune to campaign against the dairy industry, a move he says wins him respect even among fierce detractors.

“You’ve got to do what your conscience dictates. You’ve got to make choices for your own integrity and in alignment with your own soul,” he said.