One is a household name for his skills on the rugby field and marketability, and his sister is on her way to emulating him; the Williams siblings, Sonny Bill and Niall, are set for a rare double tomorrow when the New Zealand Olympic sevens teams are announced.
The announcement of the mens' and women's squads will be announced at Eden Park at 1pm and all eyes will be on whether the pair make it.
Sonny Bill, who has represented the All Blacks at two World Cups, is considered a good chance to make the men's squad to Rio by All Blacks coach Steve Hansen, who said recently that he plans to get him straight back into the 15-man code once the 30-year-old's Olympics duties are over.
Hoping to join him at the historic Games, where rugby will be played for the first time since 1924, is little sister Niall, 28, a New Zealand touch player for 10 years before making the switch to the full tackle game last year. She is a mother of two small children.
In a Herald on Sunday interview in May, Niall was asked about what it would mean to the Williams family should the pair both represent their country in Rio. "Even with me playing touch and all of Sonny's achievements, they're already proud," she said. "But the Olympics are the pinnacle of sport so, if we both made it, the family would be ... I guess words can't describe the feelings they would have, but proud comes to mind straight away.
Niall, who has a twin sister and two older brothers, said Sonny Bill was a role model for the training and dedication he put into rugby, but added that her own fitness commitments were considerable.
When her children Tatum-Lee and Rema-Rae see her play on TV, she said, "they're like 'Mummy, No 4!'. That's really cute, but Tatum, she's always like 'Mummy are you going training again?' and it's like, 'Yes, darling'.
"A lot of skills transfer over from touch, but the contact area was the hardest thing to pick up.
"But I do have two big brothers to help out with that and my whole life I've always been the harder toucher in touch. I guess it's more about attitude and learning the technique as I go."
Sonny Bill told Yahoo in May of his feelings should he and Niall get the chance to both strive for a gold medal: "We've spoken about it, I know that if I didn't make and she didn't make it our family would still be proud of both of us for being able to play for New Zealand sevens. But it would be an amazing achievement for both the siblings to go to the Olympics together."
Rugby sevens at Rio
Women's - August 6-8 (seeding in brackets)
Pool A: Australia (one), USA (six), Fiji (seven), Colombia (12)
Pool B: New Zealand (two), France (five), Spain (eight), Kenya (11)
Pool C: Canada (three), Great Britain (four), Brazil (nine), Japan (10)
Men's - August 9-11 (seeding in brackets)
Pool A: Fiji (one), USA (six), Argentina (seven), Brazil (12)
Pool B: South Africa (two), Australia (five), France (eight), Spain (11)
Pool C: New Zealand (three), Great Britain (four), Kenya (nine), Japan (10)