HOLLYWOOD is awash in dys­functional families, but the clan of former “Growing Pains” star ALAN THICKE might just top the bill!

Alan is a notorious playboy, his mother was a hopeless alcoholic, his two oldest sons are potheads, and his mother-in-law has been accused of orchestrating a murder.

“Alan and his family members have a ton of skeletons in their closets,” a source who knows the Thickes told The ENQUIRER.

Canadian-born Alan has been married three times and romanced dozens of hotties – most of whom were little more than half his age!

Now,66, Alan started his marry-go-round in 1970 when he wed future “Days of Our Lives” star Gloria Lor­ing – and former model Suzanne Stewart told The ENQUIRER that she enjoyed steamy three-way sex with them for years.

The couple – parents of sons Brennan, 38, and Robin, 36, of “Blurred Lines” fame – denied her claims. They di­vorced in 1986.

In 1988, then- 41-year-old Alan hosted the Miss USA pageant and was soon dating Miss Georgia Don­na Rampy, who was just 24.

By the following year, he was living with 20-year-old ac­tress Kristy Swanson – but they’d actually started dating when she was a teenager.

That didn’t last, and in 1991, the roving Romeo began seeing two beauty queens at the same time – 24-year-old 1988 Miss USA Courtney Gibbs and a former Miss Bulgaria who’d bared all in “Playboy”!

Alan married his second wife, former Miss World 1990 Gina Tolleson, in 1994 – when she was 24 and he was 47. They had a son, Carter, now 16, but split in 1999.

ALAN – who played psychologist Dr. Jason Seaver on “Growing Pains” from 1985 to 1992 – is currently married to mod­el Tanya Callau. When they wed in 2005, she was 30 to his 58.

Some of Alan’s kids are also hell-raisers. Pop heartthrob Robin – who’s married to “Baggage Claim” beauty Paula Patton – was recently slammed for fondling an­other woman’s bottom at a post-MTV Video Music Awards party. But pot seems to be a bigger problem for both him and his broth­er Brennan.

As The ENQUIRER reported in August 2011, Brennan was managing a medical mar­ijuana dispensary in Venice, Calif., and filed for bankruptcy in August 2010.

Meanwhile, Grammy-nominated singer Robin has made no secret about enjoying illegal substances, once telling a reporter: “I’ve never met a drug that I didn’t like.”

He was busted for marijuana possession in February 2012 when New York City cops caught him smoking a joint in a Cadillac Escalade.

“Weed is my crutch, my muse, the lesser of all evil,” Robin told a reporter earlier this year.

“I’ve spent a good $500,000 on pot…My buddy runs a store, I can get medical marijuana. When I’m at home, I’m a nonstop chimney.”

Robin also admitted that booze re­laxes him before recording, after work and even before interviews.

“Being in front of a camera makes you so sensitive and insecure, and you know, an alcoholic,” the gifted song­writer told an interviewer.

Alcoholism apparently runs in the family – with Alan admitting to The ENQUIRER that his mother, a former nurse, was an incurable lush.

“My mother Joan…has been in every possible program in two countries, three states and five cities – from Northern Ontario to Southern Cali­fornia,” Alan told The ENQUIRER in 1998.

“She’s just one of those cases that defies help.”

When The ENQUIRER caught up with Joan, she was living in a Toronto skid row shelter and admitted: “I’ve had a drinking problem for years.”

But in perhaps the most stun­ning example of dysfunction, Alan’s mother-in-law Miriam Callau has been accused of orchestrating the gruesome slaughter of her wealthy husband.

IN APRIL, she was charged as the mastermind behind the March 28 disappearance of her Dutch spouse Petrus Dekker – the stepfather of Al­an’s current wife Tanya – from their $3 million, 1,400-acre cattle ranch near Santa Cruz, Bolivia.

Dekker’s decomposing body was discovered more than a week later in a field outside the couple’s home.

He was shot four times, and his hands and feet were bound, accord­ing to police reports.

Police in Bolivia alleged Callau paid an employee $4,000 to hire hit men to kill her husband because she wanted to sell the ranch and move back to the U.S., but he didn’t.

The source added: “It’s hard to be­lieve that the family of beloved TV dad Jason Seaver has gotten into so much trouble!”