Mr Kelly, a policeman, survived the shooting in 1979.
But for a young Mrs Foster, it was a glimpse of the Troubles raging outside their otherwise idyllic childhood existence in rural Fermanagh.
"It was a very simple, happy, rural life," she said. "Hay fields and the sort of thing you would expect with a country girl.
"After he was shot we had to move."
It meant giving up their small farm, which her father ran as a sideline.
Mrs Foster still remembers the events with terrifying clarity.
"I was in the kitchen and my mother was sitting on the edge of the table and she just froze when the gunshots went off," she recalled.
"I didn't know what they were until my father came in on all fours crawling, with blood coming from his head."
She believes the man who carried out the shooting is now dead and she knows what happened.
"The terrorists thought he was on police duty and he would be coming home at 12 o'clock, but then they realised he was in the house," she explained.
"So when he went out to close the animals in for the night about 9.30pm or so they opened up. That meant they were further away than they would have been if he had come in the car."
She recalls her father describing how he "danced about" to try and avoid the gunfire until they hit him in the head.
Despite his ordeal he lived another 32 years.
It was not meant to be, she believes.
That incident and a later bus bombing when she was 16 have helped shape her outlook. She said: "It is part of who I am and can't be denied. It informed my teenage years, it informed my political decisions, but at the same time I don't think we should let the past define what we do in the future."
John Kelly had been at a football match when he met his future wife Georgina. He supported Distillery, but as a Sandy Row girl she was for Linfield.
Somehow, they hit it off from the first.
Mrs Foster takes up the story.
"After they got married they came to Fermanagh by train to Clones Junction in 1957," she said.
"Then the train was taken off and my mother was more or less stranded in Fermanagh for a while.
"I have many happy memories of coming up to Sandy Row to see my granny in the Seventies. My grandfather was a soldier, my granny was a housewife and had eight children. It was certainly a working class household."
After a spell of factory work her father joined the RUC around 1967. He was also a part-time farmer, keeping a few cattle on 10 or 12 acres near a crossroads at Dernawilt townland, Roslea.
Mrs Foster's birthday was in July, after the hay was cut, and parties were held in the field under the sun.
But it all ended as her father locked in the cows.
The gunmen had misjudged and fired from a distance, so the bullets ricocheted off walls and none were fatal.
It looked bad, though, as he crawled through the door, blood streaming from his head.
After that the family had to be moved under the special purchase of evacuated dwellings scheme.
It allowed the Housing Executive to buy homes where people had been under threat, but that took about a month.
Meanwhile, the family were given an Alsatian dog called Sammy.
"That was the best-trained dog I have ever seen," Mrs Foster recalled.
"It was very friendly, but if anyone came near my father it went absolutely bananas. It was very frightening for that month; as a child I was going to bed and pulling up the duvet hoping nobody will be able to see me if the gunmen came back." Although her father was out of hospital in a day, it left a dreadful mark on her childhood.
"One of the most difficult things for my father was the feeling that people living nearby had set him up," she said.
"We lived in a nationalist area. We had no difficulties. People would have left their bikes in our yard to get the bus at the crossroads, and that is one of the most insidious things that the Troubles did to communities like Fermanagh.
"Everyone was wondering: 'Would that person set me up'. That even happened among people who were normally good friends and acquaintances."
The forced move might have been the making of her.
In Lisnaskea she joined the Girl Guides; something she thinks built her confidence and leadership skills.
"The second thing was Collegiate Grammar School in Enniskillen. I was the only one of my siblings who went to grammar school and I was the only one of my family to go to university," she explained.
"I put a lot of that down to it being an all-girls school."
The IRA struck again when she was 16 and her school bus was bombed in an unsuccessful attempt to kill the driver, a part-time UDR soldier.
It was a very frightening episode. "I was actually sitting beside a friend's sister and I was in the inside and she was in the aisle. She was very badly injured," Mrs Foster said.
"You then had to deal with the fact that this had happened and it could have been me, because we used to fight about who sat next to the window."
Contemporary interviews reveal she showed the leadership she was learning in the Guides, telling the other girls not to panic and encouraging them off the bus.
Did these experiences drive her into politics?
"I honestly can't answer that because I haven't lived another life where that didn't happen," she answered.
"In the life I did actually live, I joined the Young Unionist Association at Queen's in 1989."
That was the Ulster Unionists, and she rose rapidly through the ranks and, as a solicitor, worked in the offices of local party stalwart James Cooper.
She left the UUP in 2004, very shortly after being elected an MLA, and that created bitterness, particularly as she was protesting against the Good Friday Agreement.
It had been signed in 1998, five years before she was elected.
"I wasn't anti ANY Agreement; I was anti THE Agreement in terms of prisoner releases, the non-accountability of ministers and the emasculation of the RUC," she insisted.
"There was no recognition of victims' issues in the Belfast Agreement. There were a range of issues that made me vote against the Agreement."
Jeffrey Donaldson, a UUP MP, also left, starting a drift, and now about a quarter of DUP members have a UUP background.
She is usually looked on as Peter Robinson's protégé, but said: "Everybody knows that Peter and I worked very closely together, but Doc (the late Rev Ian Paisley) and I had a very good relationship too.
"He always said: 'How is that poor husband of yours?' And things like that, he always had a great sense of humour."
She found the DUP warmer than the UUP.
"When my son Ben was born back in 2006 at the time of the St Andrews Agreement, he had a little heart defect," she continued.
"He had a valve problem, pulmonary stenosis, so I was in the Royal Victoria Hospital where Ben was having a procedure carried out.
"He was only three weeks old at the time.
"I always remember Doc rang me from St Andrews to say he was thinking of me in the middle of everything else that was going on.
"When I had my first daughter Sarah I don't think David Trimble (the UUP leader) ever mentioned it, though other colleagues did."
Is the DUP becoming more like the UUP now that it is led by a former member?
She is an Anglican to boot, not a member of the Free Presbyterian Church, which is still her party's largest denomination.
"We share the same core values," she answered.
"Where we go on a Sunday is never mentioned to me and that has always been the case. It was the Doc himself who actually told me: 'You are in a political party, not a church'.
"That may not have been the perception, I accept that, but it was the reality."
She is aware that the Free Presbyterians, who are only 0.6% of the population, are over-represented in the party.
Mr Robinson, her predecessor, wanted to get a mix more reflective of unionist voters. She wants to do the same.
"That is true of religious denomination and it is true of gender," she said.
"I am delighted to see more females coming into the party.
"When people don't see a woman in the leadership position then the old Hillary Clinton saying of 'you cannot be what you cannot see' comes into force.
"When you get a woman in the leadership role, as I will be, that will encourage other young women to get involved as well."
She will also take advice if she needs it.
Comparisons to Mr Robinson are treated as a compliment.
Mrs Foster added: "He has built this party in a very strategic way and I look forward to building on that success. Peter will obviously be the elder statesman of the party."
She is fairly conservative on what are called the "moral issues" of abortion and same-sex marriage, though she does feel that new abortion guidelines should be introduced to deal with the issues of fatal foetal abnormality.
She also said that Simon Hamilton, the Health Minister, should base his decision on whether to lift the ban on gay blood donations here on scientific evidence.
A decision on this will come shortly, she believes.
Political duties don't always trump being a mum.
During our interview her middle child George rang, saying he had to have a Christmas jumper for the next day. She headed off, escort in tow, to look in Sainsbury's. Family is clearly of utmost importance to her.
Mrs Foster had been hurt by suggestions that she was letting down her father's memory by sitting in Government with Sinn Fein.
The TUV had asked what her father would say about that. She has a ready answer.
"My father would be very cross about the TUV statement if he had lived to read it. It was lower than a snake's belly," she hit back.
"Daddy was incredibly proud of me. He watched every television programme that there was a chance I would be on.
"He took it very badly when anyone as much as suggested a criticism of me, never mind actually made one. He was my biggest protector."
He passed away in 2011. She still misses him greatly.
"It is difficult when someone who is such a huge figure in your life passes away before you reach the pinnacle of your career," she said.
"I am sad that he is not around to see it, but I am delighted that mummy is still here and will hopefully be in Stormont on January 11 when I am appointed First Minister."
She added: "I am confident my father would have backed me to the hilt in operating power-sharing. He didn't like Sinn Fein - the IRA had tried to murder him. So all of that was there.
"It is part of who I am and can't be denied.
"It informed my teenage years, it informed my political decisions, but at the same time I don't think we should let the past define what we do in the future.
"We should try to build a Northern Ireland that young people want to make their home in."
Martin McGuinness and Ian Paisley got on remarkably well.
When Mr Robinson took over the relationship was somewhat cooler.
Mrs Foster will take a pragmatic approach.
"I have no personal relationship with anyone in Sinn Fein but I have a working relationship," she explained.
"If there is an issue I will contact them and have a conversation about that particular issue. If you want to make things work you have to do that. It would be a ludicrous situation to be in Government and not speak to people."
What will happen after that?
She is tightlipped about political appointments - Mr Robinson is still in post until next month
"I think what you will see, in terms of my leadership, what I hope people will say is there is a party that means business in terms of promoting and defending the Union," she answered.