It was a difficult summer for the O'Neal family.
Tatum was arrested June 1 for allegedly trying to buy crack cocaine on a New York street corner, nearly ruining her yearlong sobriety. Her father, Ryan, and younger half-brother Redmond were arrested last week, accused of possession of methamphetamines during a routine check on Redmond, who was on probation for previous charges of meth and heroin possession and DUI.
While sad, it's not surprising. When it comes to addiction, the apples usually don't fall far from the tree.
"[Addiction] runs in families," Tatum O'Neal told People magazine. "I'm praying for my whole family. I hope Red will get treatment. That's what he needs. He deserves to have the life of a [young man] -- going to school, hanging out with friends, getting a job. I wish the best for him."
She knows firsthand what doctors have been saying for years: Addiction is often a family affair.
"We have very good evidence that heredity plays a significant role," Dr. Timmen Cermak, president-elect of the California Society of Addiction Medicine, told ABC News.
He explained that even if a biological child of an alcoholic was adopted and raised by non-alcoholics, statistically that child is four to nine times more likely to become an alcoholic than the general population.
In her memoirs, O'Neal described a chaotic childhood with a mother, actress Joanna Cook Moore, who struggled with drug and alcohol problems and a famous party-boy father who was often absent and emotionally abuse.
Since trying drugs at age 13, O'Neal has fought an ongoing battle with drugs and alcohol. After her divorce from John McEnroe, she developed an addiction to heroin. She said she had been sober a year when police arrested her on June 1 for allegedly trying to buy crack cocaine. She pleaded guilty to disorderly conduct.
"I was trying to relapse," she told People after her arrest. "I made a giant, horrible mistake that I regret and feel really ashamed and embarrassed about. I take full responsibility."
Ryan O'Neal, 67, denied that a vial of methamphetamine allegedly found in his room was his.
"He would never use them," his attorney Mark Werksman told The Associated Press. "We know that when all the facts come out, he should not be charged with any crime here."
Redmond O'Neal, whose mother is actress Farrah Fawcett, may have a more difficult time convincing a judge. Law enforcement officials found the substance on him and he received three years' probation in June after pleading guilty to drug possession and DUI.
He was previously placed on probation in 2005, after an arrest related to methamphetamine and cocaine possession charges.
Complicating addiction in famous families is the white-hot glare of celebrity.
"It was not just my father, but it was around where I was growing up. I mean, it's always been around me," Tatum O'Neal told CNN's Larry King about growing up around drugs and booze.
"Clearly if you are socialized in a family, in a community that is a high-drinking or high drug-use [one], then that becomes the norm to you," Cermak said.
Fame and the money that often comes with it can both help and hinder treatment for celebrities.
"Wealth can both open the doors of treatment," Cermak said. "It can also protect people from the consequences. They get a DUI, they hire a great lawyer."
Here are some other high-profile families who have struggled with addiction: