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:
If stardom came early to Drew Barrymore, so did addiction. Barrymore, now 33, has admitted that she had her first drink at age 9, began smoking marijuana at 10 and took up cocaine at 12. By the time she turned 13, she had undergone extensive drug rehab -- twice.
Acting and addiction appear to be part of Barrymore's lineage. Her grandfather John Barrymore, a star of the stage and screen in the '20s and '30s, drank himself to death at age 60. Her aunt Diana Barrymore detailed her love for booze and drugs in the 1957 best-seller "Too Much, Too Soon."
And her father, John Drew Barrymore, a sometime actor and poet who never lived with her, had a history of alcoholism and drug arrests.
After a period in her late teens of appearing nude in Playboy and making five films, Barrymore cleaned up her act, choosing a successful string of romantic comedies, becoming a Cover Girl model and getting involved with a U.N. charity.
But this summer, after her breakup with actor Justin Long, the tabloids speculated that Barrymore may have resumed her love affair with booze.
"Justin got tired of having to help Drew to the car at the end of the night," an unnamed source told the National Enquirer. "Justin gently suggested to Drew that they both slow down on the drinking, and she didn't take it well. Her inability to accept Justin's advice became the deal breaker."
Liza Minnelli and Judy Garland
It seems that for most of her life, Liza Minnelli has been trying to escape the shadow of her mother, Judy Garland.
Not only did she inherit her mother's talent for singing, dancing and acting, but she also inherited her mother's addictions to drug and drink. Garland died from an overdose at 46. Minnelli became a star in her own right but also succumbed to the darker forces of her mother's personality.
After waiting until 30 to sip her first drink, Minnelli fell deeply into booze and drugs in the hard-partying '70s. By 1984, her half-sister Lorna Luft was forced to literally kidnap Minnelli to save her from a downward spiral of alcohol, cocaine and pills. Luft wrote in her 1988 memoir, "Me and My Shadow," of how Frank Sinatra loaned her his plane to fly Minnelli to the Betty Ford Clinic in California.
She has returned to rehab a handful of other times since then, including in 2003, when she checked herself into an eight-week "self-help" program, according to Reuters.
During a 2006 interview on "The Actor's Studio," Minnelli tried to explain how she had succumbed to the same demons she had once seen her mother wrestle.
"Nobody would do that, if they had seen the things that I had seen -- unless they couldn't help it," Minnelli said. "I've won three Tonys, an Academy Award, three Golden Globes … a lack of willpower, I don't think so. This is a disease and the sooner we know that, the better."
Mackenzie Phillips and father John Phillips
It almost seemed like Mackenzie Phillips' battles with drugs were behind her. The "One Day at a Time" star saw her career, which had skyrocketed in the 1970s and '80s, suspended when she suffered two near-fatal overdoses, went through rehab several times and repeatedly relapsed.
She returned to television in the 1990s, playing a counselor on the original "90210," and recently she played a rock star mom in the Disney Channel series "So Weird."
Then came news in August that the 48-year-old actress had been arrested at Los Angeles International Airport, after police found a "small amount" of drugs and a hypodermic needle in her possession. Shortly after, TMZ.com reported that she was entering rehab -- for the 10th time.
Phillips just can't seem to escape either her genes or her past.
"I grew up in mansions, but everything was dirty and broken," she told USA Weekend magazine in 1999. "Very little was going on inside except sex, drugs and rock 'n' roll."
Her father, John Philips, founder of '60s folk-rock group The Mamas and Papas, was widely known for his heavy narcotic use. On "The E! True Hollywood Story," he admitted that he shot cocaine and heroin into his body "almost every 15 minutes for two years." Even after receiving a liver transplant in 1992, he was photographed drinking. He died in 2001 at age 65.
"Why did I survive?" Phillips asked USA Weekend. "Maybe it's to say to others, 'This happened to me. It could happen to you.' I don't mind being a poster girl."
Charlie and Martin Sheen
Martin Sheen has talked publicly about suffering from alcoholism. So when he saw his son Charlie headed down the road to addiction, he quickly sprang into action.
He recently told the AARP magazine that he turned to Alcoholics Anonymous for help. "I only got involved with AA when I was trying desperately to find a way to help Charlie, because I didn't have any skills," he said.
Charlie, who had developed a bad-boy reputation for his partying and drug use, was hospitalized for a drug overdose in 1998 when he tried injecting cocaine.
"The only way I got to Charlie, frankly, was because he'd skipped out of the hospital," Sheen told the magazine. "I had to pay the bill."
"He'd consumed an illegal substance; he was on probation," Sheen explained. "This was a criminal matter. And so that was the wedge; that was the leverage I had. That is what I took to the court; that's what I took to the sheriff. It was the only way I got him."
After a warrant was issued for his arrest, Charlie signed up for rehab.
Daniel and Stephen Baldwin
In the famous Baldwin family, with brothers Alec, Daniel, Billy and Stephen, the glare of Hollywood is a fact of life. And so, it seems, for two of the brothers, is addiction.
Since taking his first hit of cocaine in 1989, actor Daniel Baldwin has been marred by failed attempts at sobriety.
His drug problem started making headlines after a very public overdose in New York City's historic Plaza Hotel in 1998, and he had another very public relapse in 2005 on VH1's "Celebrity Fit Club," on which he erupted during filming. Daniel admitted to becoming addicted to pain medication and eventually left the show.
ABC's "Primetime" followed Daniel through rehab last year, when he admitted that he will always be an addict: "The addict will always be there, forever. I am an addict. That's just the way it is."
His younger brother Stephen, also an actor, has written about his struggles with drug addiction in his book, "The Unusual Suspect." Going to rehab introduced Stephen to Christianity and since then, he has become a born-again Christian.
"It's real. It's changed my life. It's transformed my heart. I'm not who I was," Stephen said.
ABC News' Lauren Cox and Rena Furuya provided additional reporting.