Sibling rivalry is not an alien concept to anyone with a brother or sister, but for twins Andy and Owen Liow and brothers Kai and Thor Olafson, it has taken an added dimension - a national one to be exact.

The Liow twins and the Olafson brothers will be competing at the 9th Asean Schools Games (ASG) in Singapore over the next week.

Identical twins Andy and Owen, 17, have no doubt that the friendly rivalry has pushed them to improve their basketball game.

"We argue about who contributed more after every game," admitted Owen, the younger twin by 30 minutes, adding that neither of them "like to lose".

On the court however, the rivalry takes a back seat and their likeness becomes an advantage.

"Sometimes, the person who is supposed to be guarding me will suddenly switch to guarding Andy, leaving me unmarked," Owen recalls.

"When that happens he will always pass me the ball."

However, they were quick to refute suggestions of a special telepathic connection between them.

"We know what each other likes to do since we have been training together since young, so naturally we will help each other when we play," said Andy.

Inspired by their older sister, Hui Ting, 23, who represented Singapore at the Under-16 level, the Liow boys have always dreamed of playing basketball together at a national level.

Owen explained: "Our home is full of her medals from all the different competitions she participated in.

"We have always wanted to be like her, to bring back a lot of medals and make our family proud."

Similarly for swimmers Kai and Thor, competition so close to home is what keeps them on their toes.

"This year was the closest I've come to beating him in the pool," said Thor, 15, the younger Olafson.

"But you still lost," 16-year-old Kai reminded him cheekily.

The Anglo-Chinese School (Independent) students, who are of Canadian and Norwegian heritage, spent their early years in Thailand.

They started to swim competitively only after coming to Singapore in 2007.

The duo, however, confessed that in the pool, they prefer the more action-packed water polo over swimming.

With no water polo in the upcoming Games, Kai will instead be competing in the 50m freestyle and Thor in the 50m backstroke.

Nevertheless, ACS(I) water polo coach Lau Kum Wang, 55, is confident of the boys' medal chances in their events.

"In (water) polo we focus a lot on explosive training, so for short bursts and sprints like the 50m events, they definitely have a shot."