Kyle Paisley recalls a particularly dramatic re-enactment of the Old Testament story when he was five years-old in which God commanded Abraham to kill his son Isaac.

His twin brother, Ian junior, now a Democratic Unionist Party MP, played the role of the patriarch wielding a garden fork. “I’ve the scars to prove it,” Kyle remembers.

Sitting in a Belfast hotel this week with Kyle, Ian jnr laughed as he displayed his Biblical knowledge: “You lived. Like Isaac, you lived.” The two celebrated their 50th birthdays in December

Ian is no longer called “junior” following the death of his father, or, at least, not as often. Today, he holds the North Antrim House of Commons seat, first won by his father in 1970.

His twin, however, took a different road, but one also laid down by the late Rev Ian, who died in 2014, becoming a minister in the Free Presbyterian church founded by his father. Rev Kyle, more softly spoken and physically slighter than his twin, is a minister at Oulton Broad Free Presbyterian Church in Lowestoft in Suffolk in the east of England.

Passing the half-century mark has made the twins reflect on their lives, but also on the life led by their father: “Even by that stage he’d achieved a lot, but the best was yet to be,” says Kyle.

Bible texts Born in 1966, the twins were unsurprisingly steeped in biblical texts throughout what they describe as a carefree childhood at the height of the Troubles during the 1970s.

He had to be really tough to be credible during the really dark days so he could with credibility take the bolder steps that had to be made later on However, the picture they paint of their childhoods and of their father’s place in their lives is one greatly at odds with the “fire and brimstone” persona he projected publicly for decades. Instead, they remember games of football with him in the garden of their Cyprus Avenue home, shared with their three older sisters, Sharon, Rhonda and Cherith, and mother Eileen.

He was not strict but “quiet”, remembers Ian: “He had to be really tough to be credible during the really dark days so he could with credibility take the bolder steps that had to be made later on.

The two are together in the Stormont Hotel, across the road from the Stormont parliament – a place now descending into “deep freeze”, as Ian puts it, following British prime minister Theresa May’s decision to call an election.

The two believe Ireland will follow the UK out of the European Union: “I think Ireland will realise soon that staying in Europe isn’t for them.

“I think it’s going to be out of Europe probably a few years after Britain,” Ian jnr says, adding that EU membership has not been good for Ireland, “North or South”.

“When they realise most of their trade for foreign direct investment is with the United States and most of their homegrown trade is with Britain, why would they pay billions of pounds to be in a membership which isn’t actually delivering trade to them?” he says.

His views have been coloured by conversations with people in the Republic, he insists: “Look what’s happened. No-one thought Trump would ever win.

“No-one thought Le Pen would even get close and she’s in a sniff of being president of France: The impact that’s going to have inside the EU. No-one thought Brexit. Why not Irexit?”

Ian Paisley with his twin sons, late 1960s. His brother, who describes himself as “an Irishman in England”, agrees, believing that an “Irexit” could happen in the years ahead, even if the prospect is doubted now.

If I’m your supporter you’ve got a rock behind you, not a rock on top of you, and people should recognise that The Assembly elections last March, with the Renewable Heat Incentive (RHI) scheme scandal at its height, saw Sinn Féin under Michelle O’Neill emerge with just one seat less than the DUP. This week, however, Ian Paisley defends DUP leader, Arlene Foster: “She really went through fire, probably fire that she’d never been through before in terms of being tested as a politician and as a leader.

“That I know has been probably a hard lesson but I think lessons have been learned,” he says, “I certainly have told her that I am not her enemy, I am her supporter.

“If I’m your supporter you’ve got a rock behind you, not a rock on top of you, and people should recognise that,” says Paisley, who surprised many by the warmth of his words of tribute following the death of Sinn Féin’s Martin McGuinness.

Northern Ireland’s political parties do not need a Northern Ireland Secretary chairing the talks, he says. The DUP has “no red lines” in the talks, and is up for a deal. “Unfortunately now the circumstances are not lending themselves to that.”

Same-sex marriage Turning to social issues which divide opinion in the North, Ian jnr doubts if he would ever support same-sex marriage or abortion, even if his own party shifted position.

Meanwhile, Rev Kyle was surprised the 2015 marriage equality referendum in the Republic passed so easily, “which shows you that the authority of the [Catholic] Church has just dissipated”.

The way I see it is the best way to communicate with somebody is in the language that they best appreciate On the dispute over the Irish language, he acknowledges that he did not understand all of the financial and political costs of the Irish language act demanded by Sinn Féin.

“But just on a simple principle . . . the way I see it is the best way to communicate with somebody is in the language that they best appreciate,” he said.

“I don’t believe in pouring endless amounts of money into anything when there are other more serious issues like health to deal with, but I don’t believe in making excuses for not helping people in their education.”