THE man who most influenced me in my life was long dead before I was born.

My maternal grandfather, Patrick, died in 1967. His war wounds killed him in the end. He'd been badly injured in the First World War and then badly injured again during Dunkirk. A boy needs the platonic ideal of a man to follow as a guide in life - a person to aspire to, to learn from. My grandfather had manliness to burn: a boxer, a communist street-fighter in London in the 1930s, a hero in two world wars.

But there was more to him than fists and bullets. He was a gentle man. His only daughter, my mother, was born towards the end of the Second World War. By the time the summer of 1945 came around, the shrapnel holes and burns in his body left him a wreck. No more boxing, no more taking on Blackshirts, no more working on the doors of rich hotels where he earned a living bouncing drunks when he wasn't risking his life for his country.

His Irish wife, my grandmother, became the sole breadwinner for the family living in the slums of London's east end. She worked three jobs most days, while Patrick stayed at home and raised his baby daughter, wheezing from his war-ruined lungs as he lifted the child to nurse her.

Patrick changed from a man of action to the most doting father I've ever heard of. He washed, dressed and played with his daughter, took her to school, taught her to read - and gave her a code and a sense of honour. While her mother, who loved her, was stolen from the family by work every day and most nights, and unable to shower her child with kisses and cuddles, Patrick made the world a place of kindness, affection, learning and care for his child, despite poverty and pain.

This "Act Two" of his life - which my grandmother, with some sadness and maybe a little envy, told me he called "motherhood" - made him the happiest he'd ever been. Raising a baby into a girl and then a woman fulfilled him more than an all that travelling, fighting, killing and swagger.

Who wouldn't want to be this man? I didn't want his pain and suffering - but I wanted the simple decent nobility with which he faced life. He may not be here, but he has guided me over the last 40-odd years every day. In fact, the notion of him as the idealised father figure lies behind the radio series I've just finished making for BBC Scotland about what it means to be a dad in 21st-century Scotland.

My own dad has a role in the creation of that series too. My father and I had a fraught relationship to say the least. My memories of my childhood in Ireland - for by the time I was born the whole family had abandoned London and gone back home, just in time for the British Army to march into Belfast - are bitter and unhappy. There was a lot of drinking, some violence and little love. Life was drama, not peace; words were shouted, not spoken.

If I had to hazard a guess at what troubled my father it would be that he married too young, had me too young. He'd been abandoned by his own mother, too - born illegitimate, he spent his early years in foster care. It's an explanation, not an excuse. My wife's uncle had an almost identical boyhood to my father and grew up to be a kind, loving dad, whose children wept their eyes dry at his funeral a few years ago. I cried with them because their love for him was proof of his decency and the loss of any decent person is a loss to us all. Life experience doesn't have to drag you down; if you're good in your heart you can rise above anything, I believe.

I don't want to beat up on my dad, though, all these years later. We've talked our past over, got nowhere, and come to a sad and distant detente. I'm sure it makes my father as unhappy as it makes me.

Back when I was little, and didn't have the words or thoughts to express the need any young child has for a positive male role model in their life, I used to dream - literally - that my grandfather was alive, and that I was able to spend time with him. Somewhere in my psyche, I knew I needed a man in order to be a man, and so I got my grandmother to tell me stories of Patrick every day. She never tired of talking of her much-loved husband and I never tired of hearing about him, as the stories made me feel as if he was with me - and I learned how to be a man, or as good a man as I could ever be, from those stories.

In my mid-teens - those times when you feel very alone and misunderstood - I took to trying to contact Patrick on a Ouija board, to ask him advice. Maybe a ghost would be a better father than the one I had. The memory makes me feel stupid and sad for my younger self, and sorry for my own father unable to reach out to his son.

When I wrote my first novel, which explores the bitter relations between children and parents, the only autobiographical element of the book was a side story which took the life of my grandfather and commemorated it - the rest was imagination. It was my heart-sore thank-you to the man who helped build me; a man who I still grieve for despite having never seen him or touched him.

When my own daughters were born in my mid 20s, I swore an oath to myself on my life that I would be my grandfather Patrick in all I did and thought, not my father. If I learned anything from my father, I learned it in reverse: what he did, I didn't; what he omitted, I completed. I set fatherhood ahead of everything in my life. All human life is tinged with failure, but I was not going to fail at raising my daughters. My own lost relationship with my father and the deep, lonely link I had to my dead grandfather over the gulf of time have nagged at me throughout my life, and ­influenced the way I live - even the way I do my job.

I've been a crime reporter most of my career, since I first started in journalism in Belfast in 1991. My job allows me to be a voyeur, it allows me to study human lives, often in extremis. I don't see the cast of characters who pass through my notebook simply as criminals, or cops, or victims, however, but always as human beings. I want to know what they were like as fathers, mothers, sons, daughters - in the ordinary moments, before their lives became extraordinary and they found themselves in the glare of publicity. Often, I've found that lurking at the heart of any human story is the relationship, or lack of it, which they had with the man they called their dad. A great dad can build, a bad dad can stunt, a dreadful dad can ruin.

My daughters are getting into their late teens and bound for university soon, and in the last year or so I have found myself looking back over my own childhood and my own term as a father and trying to make sense of what shaped me more as the human being I am today: being a son, or being a dad?

And so, I set to work on my radio series called Being Dad - investigating the lives of gay dads, jailbird dads, stay-at-home dads, second-time-around dads, disabled dads, single dads; exploring modern masculinity through the prism of fatherhood. I wanted to see if other men found the concept of fatherhood quite as tortuous as I do - tortuous in terms of the failure of the past that I remember in my own childhood, and tortuous also in the terror of the present: that I cannot and will not repeat the mistakes of the past.

For those reasons, I both love and hate that poem by Philip Larkin, This Be The Verse. Those lines: "Man hands on misery to man. It deepens like a coastal shelf. Get out as quickly as you can, and don't have any kids yourself." Taking Larkin's words as direct familial warning, I have struggled hard not to fill my kids with the faults I have - and I've struggled to purge myself of the faults my own father handed down to me.

What I learned from the many men I spoke to was that fatherhood does not redeem - it cannot redeem - but it does change a man, no matter what type of man they are. Sadly, the changes wrought by fatherhood on a man often remain locked away in his mind and are never shared with the children who changed him. I heard my own father say just these words to me, but too late for both of us.

Let me give you an example: after all, a good story is worth a book full of theory. I spent the bulk of my career covering the Troubles in Ireland. A good few years ago, I flew back to Belfast from Scotland after a spate of particularly nasty killings to write a series of articles on the sorry state of my country.

One of my first ports of call was a longstanding contact of mine in the UVF - a Protestant terrorist gang. He was high up in his organisation. I can't give you his name - as he's still alive and would have me killed if I did - but he had a nickname: The Crucifier. In paramilitary-controlled areas, the terrorists act as the police. Back in the 1970s, my contact was the local go-to guy. One young lad had mugged a granny. The kid's dad came to my contact and asked him to sort his son out. That's what happened in those days - justice was dispensed, usually in the form of a beating, or at worst a knee-capping, unless you were a traitor and then it was a bullet in the head.

This father, though, failed to tell my contact what he would like done to his son. So, my contact, incensed by an attack on an innocent old lady came up with his own idea. The next the father heard of his son was a wail coming from his own backyard: the lad had been nailed by his hands to his back fence. Thus the nickname: The Crucifier.

I was sitting in The Crucifier's living room, talking over the shootings and killings. I used to bring a bottle of Bacardi to our chats to oil the wheels of conversation. He was getting drunker as the night wore on. Soon, business was concluded, and we stopped our talk about murder and terror, and just found ourselves chatting: two men, talking about our lives, our kids, our wives, our work.

The Crucifier went upstairs and came down with a bag of grass and a gun with a homemade silencer. He rolled himself joint after joint and started to strip and rebuild his pistol, cleaning it. A little drunk myself, I asked him how his wife and kids coped with his life, with what he did. At that moment his eyes iced over and he snarled, "Who the f*** do you think you are? Why should my life hurt my children anymore than your life hurts your children?"

I was sat on one side of a coffee table, he on the other. He lifted the pistol and aimed it at my head. I didn't even have time to say "No" before he pulled the trigger and the gun blank-fired with a dull clunk. Unnoticed by me, he'd deftly slipped the magazine from the butt of the pistol while we were chatting, so there were no bullets in the gun. He laughed after he played his mock execution game with me, and we went back to drinking. He finished his Bacardi and said: "I do worry about what my life will do to my kids, though."

We poured another drink and for the next hour he cried and talked about his fear that he'd turned his sons into monsters who killed like him, that he'd end up in prison and not be able give his girls away at their weddings; that the IRA would break in through his armoured front door and shoot him dead in front of his family. "I don't want to ruin my children's lives," he said. And he sobbed as hard as I have ever seen another man sob. I felt for him - even though he had pointed a gun at my head and I hated everything he stood for.

Don't get me wrong - his love for his children didn't redeem him; just because you're a good father it doesn't wash away your sins. But in that moment, there was a burning example before me of what fatherhood could do to a man - even this man - for the better, and it has stayed with me to this day. This gunman was a dad, just like me: scared and inept and trying to make sense of his own life while not destroying the lives of the children he loved. For me, this story stands as the most important proof I have seen of the power of fatherhood to touch and change even the most cursed and hateful creature.

I tried very hard to give up the wicked, selfish side of myself when I became a father. Not for redemption's sake, but because I simply didn't want to do what my own father did. I wanted to walk in the footsteps of my grandfather. I knew soul-deep that fatherhood topped everything: career, wealth, power, sex, my own life and death - it all meant nothing if I couldn't look myself in the mirror and think I'd tried my best to be as good a father as I could be - and that meant not marking my children's lives through my own failings as a human being. I desperately hoped, when I made my radio series about dads, that other men were the same. That they felt as I did - that all we've got to give is honesty, tenderness, guidance, love, friendship, self-sacrifice. The feminine side of ourselves, as some would say. The better side of ourselves, I would say. In fact, self-sacrifice was the good part of it - I couldn't be a father I thought unless I gave something up, suffered something, lost something. So much of love is suffering.

We live in a world, however, where motherhood is idealised while fatherhood plays second fiddle. Fatherhood should be idealised too, recognised as just as important a calling. I get angry that men are made to feel - by themselves, their friends, everyone - that fatherhood is something we shouldn't talk about as much as women talk about motherhood, when there is no bigger vocation in the life of any man with children than being a good father to those children. To become good people, children need good men just as much as they need good women.

There was one thing I learned from all those dads I spoke to for the BBC; it was a very simple thing and made me very happy: they are all trying. Yes, there are still plenty of failures out there - across every class and in every town - but most men are trying very hard to be the fathers they imagined themselves to be. They are trying hard to live up to their own expectations, to break the bad links with the past and their own fathers if those links need to be broken, and to build better ways of being men by the way they raise their children.

There's a long journey ahead for all the fathers of the future - a journey that will never end because humans will never be perfect - but the men of today are maybe half-way there and I think we've done the hard work, so that our great-great-grandsons, when they have kids, will find it easier than us, who found it easier than our fathers, who found it easier than their fathers. Hopefully, fatherhood becomes a gift that men hand down to other men for the rest of the time that this species of ours walks about on this planet.

If it is a gift, though, then I have learned that fatherhood still sadly comes wrapped in a lot of pain. The pain of memory, of expectation, of regret and inadequacy. If a father is the platonic ideal of a man, then what man can ever live up to that, in his own eyes or the eyes of his children. I wish that would change. I know I can never live up to my grandfather, but I hope my daughters and their children never doubt that they can live up to me.

Being Dad begins on BBC Radio Scotland on Thursday, November 14 at 1.30pm and runs every Thursday for six weeks. Neil Mackay is the Sunday Herald's Head of News. His novel All The Little Guns Went Bang Bang Bang is published by Freight Books priced £8.99