With one brother playing for the Meath footballers, another for the Royal County's hurlers, and the youngest destined for a career in professional rugby, it's fair to say that the O'Sullivan household is extremely competitive.
Hugh O'Sullivan might well have followed the lead of his brothers Cillian and Mark, but instead the lure of rugby was too much.
It helped too of course, that O'Sullivan won two Senior Cup medals with Belvedere College in the last two years, but the Meath minor footballers were also keen to get him involved.
"It was sort of at minor level," he recalls. "You either go there (GAA) or to the Leinster underage system and Cillian went with the football.
"There was certainly an opportunity after one of the Cup campaigns. I could have went in with the Meath minors.
"I would have loved to have done it but I was very conscious... my brother was out for a long period with a back injury and was overloaded so I was really conscious of spreading myself over thin paper.
"I really enjoyed the rugby in Belvo and obviously I had been involved with Leinster. I had two years at 18s schools which is quite rare. I felt like I had a shot at it.
"Then I played with the Leinster 20s a year early as well. It spiralled and to win two Cups in a row, it's really hard to walk away."
Growing up in Meath, GAA dominated but rugby slowly took a hold. O'Sullivan had already played for his county at U-14 and U-16 level and while his brothers were making inroads in the GAA, he went down a different path.
"On my mam's side, my grand-dad played down in Sunday's Well I think. But there wasn't much connection there," he admitted.
"My brothers played. One of them went to Castleknock and the other Belvedere. Cillian was saying - he was interviewed before the Monaghan game at the weekend - that he recalled being run over by Dan Leavy two years in a row.
"They didn't have a great team in school so it didn't work out for him. They got hammered by Michael's in the first two rounds.
"By chance then, by the time I came along, we had a really strong team. That helps. When you're successful... jeez, he dreamed of winning a Cup as well but I just got the chance to do it.
"It was great when we were growing up because I had seen them be in a sort of professional environment so you know what to expect and they'd be telling you a bit about what's going on. It was a good insight to have."
Despite playing at full-back in school, O'Sullivan has long been seen as a scrum-half and will continue in the No 9 shirt for the Ireland U-20s against Wales on Friday.
"I would be much more aware of the values of the team and stuff like that," he added.
"It goes hyper-structured here (U-20s) and it's all about the detail but it's important not to lose sight of the relationship between the team and the value of that. Sometimes that can get lost a bit."
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