Leonard, who found global fame playing Spock on Star Trek, was hardly at home during Adam's formative years.

He told the Jewish Telegraph: "He was distant and was very concerned and focused on his work.

"When he was filming Star Trek, he would be working 13-hour days - he would come home, have his dinner, learn his lines and go to bed."

Children of celebrities have often found it hard to make their own way in life and have struggled to battle their demons.

Actor Pierce Brosnan's son Chris was in trouble with the law and battled a drug habit, while singer Rod Stewart's son Sean is a recovering alcoholic.

Adam, who lives in the Santa Monica area of Los Angeles, said: "It is so difficult to create you own identity.

"I am not Leonard Nimoy or Spock, nor was I part of Star Trek.

"It is such a struggle to stand on your own two feet."

But despite their ups and downs over the years, father and son have become close in more recent times.

Adam, 52, recalled: "It was fabulous when my father first became famous - I used to give out his autograph at school.

"But I was very shy and it did not particularly help that my father was so well-known. "I remember telling a classmate at Hebrew school that Spock was my dad. This was around 1966, and he told everybody.

"I did not like the attention - I was just content to keep a low profile."

Adam battled with a drug and alcohol addiction for 30 years, beginning when he first smoked marijuana at the age of 17.

The addiction became so bad that it ended his television directorial career as well as his 18-year marriage.

He tells this story in his debut book, My Incredibly Wonderful, Miserable Life: An Anti-Memoir.

Adam said: "The addiction has a detrimental effect on my career.

"There were situations where I would not partake in smoking cannabis or drinking alcohol and when you are in withdrawal, it makes you a very unpleasant person.

"When I was directing, I was not fun to be with on set, I had a difficult time controlling my temper and attitude.

"I could not deal with issues that arose in a tactful manner."

Adam and sister Julie are the children of Leonard's first marriage to Sandra Zober.

Raised in a traditional Jewish home in Los Angeles, the family was not observant but kept the festivals and Adam was barmitzvah.

But Adam has embraced his religious side in latter years and studies Torah with a rabbi on a regular basis.

"I love Judaism - I lead the seder at Pesach and I fast on Yom Kippur," he added.

A graduate of LA's Loyola Law School, he practised as a music and entertainment attorney for seven years, but quit after being frustrated by the lack of creativity in the role.

Adam said: "Because of who my father is, people looked at me in a critical manner.

"They wondered if I was talented at my job and I had to deal with people who had an issue with that.

"I did not enjoy the lack of creativity involved in the industry either.

"Many music labels folded, merged or moved to New York and the job became stressful and competitive.

"People think there must be a lot of creativity involved working as a lawyer in the entertainment business, but it was just not that interesting."

His career change began in 1988 when he enrolled to study filmmaking at the University of California, Los Angeles, and acting with his father's friend Jeff Corey.

Adam explained: "That decision changed my life.

"I wanted to work behind the camera, not in front of it like my father, although he proved to be a valuable resource for me.

"I want to hone my skills and learn what made actors tick and learn about their needs."

He went on to work on successful TV series such as NYPD Blue, Babylon 5 and Star Trek: The Next Generation.

But, due to his addiction, his career and 18-year marriage to wife Nancy fell apart.

"I got to a point where I did not know where I was," Adam remembered.

He admitted that living in LA did not help his situation, either.

Adam said: "You have to look hard to find meaningful relationships here.

"It is such a huge city and one that is so spread out that it is hard to put roots down."

He decided to change his life around in January, 2004, when he entered a rehabilitation programme aimed at achieving a major attitude adjustment.

He then joined the Los Angeles Poets and Writers Collective and soon became a devotee of method writing.

Adam continued: "I had been keeping journals since I was at university and realised I had the makings of a book.

"I shopped to more than 50 publishers but I found one that agreed to take it on."

He has taken his two children, 18-year-old Madeline and Jonah, 17, to family counselling in a bid to guide and support them.

And he still has what he calls a "congenial" relationship with ex-wife Nancy.

Adam said: "I feel that I should put them first and I focus on them."

But his parenting skills were tested in the summer when he found out he was the father of a 30-year-old lady living in New York.

He revealed: "Her name is Morgan and she has a two-year-old son called Charlie, so I am an instant grandfather, too.

"I was promoting my book in New York and met up with a girl I dated in college, who told me about our daughter.

"I was shocked to say the least - it was not easy. I had a lot of fear.

"It was weird and awkward meeting up with her, but it went well and she is a great girl."

Adam is busy forging ahead with life and, as well as his writing, is currently teaching acting and directing at the New York Film Academy located at Universal Studios, in LA.