National Siblings Day: Why youngest siblings are most likely to be parents' favourite

In the battle of the siblings, fighting for their parents’ attention, it is often presumed that the first-born is the favourite. How can you compete with their very first child, after all?

But according to a new study, the youngest sibling is in fact more likely to be the parents’ favourite.

However, it actually all comes down to perceived favouritism.

Researchers from Brigham Young University's School of Family Life have concluded that favouritism is in fact in the eye of the beholder.

Essentially, if a younger sibling feels like they’re the favourite and their parents agree, the parent-child relationship is strengthened. If they don’t think they’re the favourite, the opposite happens.

For older siblings, whether they’re considered to be the favourite or not has less of an effect on their relationship with their parents.

The researchers believe this is due to social comparison, with younger siblings placing more emphasis on comparing themselves to their older siblings.

“It’s not that first-borns don't ever think about their siblings and themselves in reference to them,” says BYU School of Family Life assistant professor Alex Jensen. “It’s just not as active of a part of their daily life.

“My guess is it’s probably rarer that parents will say to an older sibling, ‘Why can’t you be more like your younger sibling?’ It’s more likely to happen the other way around.”

The researchers drew their conclusions after studying 300 families each with two teenagers.

The children and parents were asked various questions to assess levels of favouritism. The parents were asked how much warmth and conflict they have with their children, while the teenagers were asked to describe their relationship with their parents.

The researchers found that on the whole, children had both more warmth and more conflict with their mothers, but the rates of change in relationship for both mother and father were similar.

Middle children may be wondering where they come into all this, having been neglected (as usual).

Jensen believes the results of the study would be similar for larger families.

“If you had to ask me, ‘Do we see the same thing with the second born and third born?’ I think probably so,” Jensen says. “The youngest kid looks up to everybody, the next youngest kid looks up to everyone older than them, and it just kind of goes up the line.”

And if you’re a parent wondering how to deal with all this and bring your children up in the best possible way, Jensen says treating your offspring all equally is not necessarily the best approach.

“When parents are more loving and they’re more supportive and consistent with all of the kids, the favouritism tends to not matter as much,” Jensen says. “Some parents feel like ‘I need to treat them the same.’

“What I would say is ‘No you need to treat them fairly, but not equally.’ If you focus on it being okay to treat them differently because they’re different people and have different needs, that’s OK.”