When music teacher Aaron Low noticed that his two sons were forming a clique, excluding their two sisters, he started rostering a different kind of family outing.
Every month, the 38-year-old would take each of his four children out in turn. However, in July, this dad-and-me time morphed into party-of-three affairs.
"I deliberately made a schedule so every one of them could go out in different pairs. I have a roster kept in my phone," says Mr Low, whose wife Grace is expecting their fifth child, a girl.
He appreciates that his sons Gabriel, 10, and Gaius, eight, are bonding over interests such as basketball, badminton and playing the ukulele. But he also wants his sons to "relate more" to their two sisters, aged nine and four, so it is "not just boys and girls".
Cliques among siblings are "not particularly significant in sociological terms, especially as there have been far fewer large families... over the past 50 years", says sociologist Stella R.
Quah from the Duke-NUS Graduate Medical School, who adds that parents cannot do anything about siblings forming cliques and that they are not to blame.
"The number of children has diminished and therefore any problems between siblings are less significant now. It's mostly families with two children now in Singapore."
Still, they are not uncommon, interviews with families by SundayLife! showed, and gender-based groupings are only one permutation.
Unlike Mr Low, most of the parents interviewed took a more hands-off approach to managing clique dynamics, intervening as a last resort, usually when fights and quarrels erupt.
Housewife Gaye Chan, 44, who has three girls, says: "I find that sometimes when we intervene too much, we lose that opportunity in which the children learn to manage conflict."
Counsellor Chang-Goh Song Eng, head of Reach Counselling, says: "As far as possible, parents generally do not need to step in, unless after careful observation over time, they notice behaviour that may be damaging to the child's development, for example, bullying among siblings."
With five children, including two sets of twins, manager Chew Chin Wee says cliques among his offspring, aged between six and eight, are "gender and age-related".
His three girls are able to talk about "things pertaining to primary school", whereas their brothers are still in kindergarten, says the 41-year-old.
He adds that he has not observed any strong affinities between his fraternal twin children - one pair of girls and one pair of boys - who have "very different" personalities.
Although his eldest daughter Koh-San, the only non-twin, says she sometimes watches television by herself, his wife, property agent Sabrina Goh, says cliquing is not particularly pronounced and that the siblings generally play together.