London - Ireland coach Andy Farrell once joked his son Owen never beat him at anything, even tiddlywinks.
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Owen Farrell is the England captain and can have the last laugh by inflicting his father's first defeat as Ireland head coach and end Irish hopes of both the Triple Crown and the Grand Slam in Sunday's Six Nations clash at Twickenham.
It will be a different atmosphere to the last time the Farrells were in a stadium together for a Test.
Andy admits his "nerves went through the roof" watching Owen and his team-mates produce their best performance under Eddie Jones in beating two-time defending champions New Zealand in last year's World Cup semi-final.
Farrell, 44, was an England fan for the day because Ireland - at the time he was their defence coach - had been soundly beaten by the All Blacks the week before.
"Now that was tough," Farrell said earlier this month.
"I was back to being a parent again and that's tougher than being a coach against your son.
"I actually did the whole fan-family thing that day on purpose, to get back to how it felt before all this ever happened."
"All this" encapsulates quite a lot.
At the 2015 World Cup, Farrell was defence coach and his son a key player as England fell at the pool stage.
Eddie Jones, who had coached Farrell senior at Saracens, came in to replace Stuart Lancaster with England and opted to let the father go, saying thinking the family dynamic would not work.
Yet father and son are used to setting aside family ties when it comes to sports.
"We're very competitive, yeah," Andy told World Rugby in a joint interview with Owen back in 2008 when they were both playing for Saracens.
"He (Owen) says he never lets me win but I always win anyway.
"He never wins anything. Even playing tiddlywinks tomorrow I would never let him win."
For Owen's uncle Sean O'Loughlin - a Wigan legend who was an unwitting Cupid when Colleen and Andy babysat him as a child - the England skipper has inherited his father's best characteristics.
"Andrew had all of the traits Owen has got now as a player and he's got them as a coach as well, so Owen has learnt from the very best," O'Loughlin told Sky Sports last November.
"One similarity would be that determination and competitiveness."
Owen showed this single-minded focus when he replaced Andy after the latter was injured during a Saracens game with Australian outfit Western Force in 2008.
"He wasn't bothered about my injury," said Andy with a smile.
"I couldn't really think about anything else other than my job," said Owen.
Owen was only ever going to play rugby, although due to his father's stellar career in rugby league with Wigan it appeared it could be that code the son took up.
Then, in 2005, Andy moved south to Hertfordshire and switched codes by signing for Saracens.
"He was kicking and screaming when we came down here ," Andy told the Daily Mail in 2017
"He didn't want to leave Wigan because he was playing league. But that lasted about two weeks.
"We planned for him to go back up north on the train every weekend, to carry on playing league.
"He did that once or twice but then I took him to training at Saracens and he soon forgot what he was missing out on."
Only 16 years separates Owen from Andy and mother Colleen and the relationship between the father and the son is not a traditional one.
"Owen and Andrew's relationship wasn't really like a father-son relationship," Andy's former Wigan team-mate and now the club's general manager Kris Radlinski told The Daily Telegraph last year.
"It was more like a best friends' relationship, and it is to this day."