The Yokoyamas welcomed another world champion into the family, after Adelia Naomi Yokoyama won the bowling women's masters gold medal for Singapore at the 2017 Deaflympics on Saturday.
She joins elder sister and 2012 Optimist sailing world champion Yukie in standing atop the world.
"I'm extremely happy but also speechless. No words can describe how happy I am," said the 18-year-old, the youngest of three sisters, via a WhatsApp interview.
She defeated women's all-events champion Kim Jieun in the final by 230 to 169 pinfalls.
Compatriot Kimberly Quek joined her in securing the Republic's first medals of any kind in the Deaflympics with a bronze in the same event.
The 23rd edition of the quadrennial competition, held in Samsun, Turkey, ended yesterday.
Singapore's chef de mission Loh Eng Meng described both medals as "out of his wildest dreams".
"We had hoped for one of them to bring back Singapore's first Deaflympics medal, but for both to win and to see our flag being raised for the first time... the feeling is indescribable," he said in a statement.
The two medals saw Singapore climb to 30th of 97 countries in the overall medal tally.
Russia topped the rankings with 195 medals, including 83 golds.
Naomi's historic victory was greeted with delirious joy in the Yokoyama household.
Said elder sister Yukie, 20: "We are all so proud of her. She was so calm and composed in the final.
"Being born deaf is obviously not easy to deal with in everyday life.
"We (in the family) are the happiest because we know just how much effort she put in for bowling."
Eldest sister Natasha, 22, is also a sailor who represented Singapore internationally.
Naomi's hearing aids, which cannot be exposed to water, meant that she could not follow her sisters into sailing.
However, her true calling was unearthed after a family friend took the sisters bowling when Naomi was nine years old.
"We (Natasha and Yukie) are both terrible bowlers and we could see that she was better than us immediately," said Yukie.
Singapore's Deaflympics team of five bowlers and four officials return to Singapore on Wednesday and will touch down at Changi Airport Terminal 1 at 5.55pm.