Why won't my child share?

The birthday party. The playdate. The back seat with one tablet and two children. Few things make a parent wince faster than a small voice shouting "Mine!"

If your young child won't share, here is the reassuring news: that is typical for their age, not a sign that something is wrong. The research also points to a few simple things that seem to help. Here is what we found.

At what age do children learn to share fairly?

Later than you might think.

A well-known study published in Nature in 2008 looked at children aged 3 to 8. Most 3 and 4 year olds acted selfishly. Most 7 and 8 year olds preferred an equal split. In other words, fairness grows a lot during these years.

So a three year old who grabs the biggest piece is doing what most three year olds do. A seven year old who insists on exactly equal halves is, too.

Do young children know they should share?

Yes, and that is the surprising part.

A 2013 paper asked children what was fair, then watched what they actually did. Children as young as 3 said everyone should share equally. But they didn't share equally themselves until about 7 or 8.

Even more interesting, the younger children correctly predicted they would keep more for themselves. So it doesn't look like a simple slip of willpower in the moment. They knew the rule, and knew they wouldn't follow it. This pattern fits the 2008 study.

For parents, this "know but don't do" gap is a relief. Your child has probably heard the message. Their behaviour simply hasn't caught up yet.

Should I make my child share?

It is tempting. But a study with preschoolers suggests a gentler route may work better.

Some children were given the choice to give up a sticker they valued. Others were told to share it. Later, the children who had chosen to give shared more with a new puppet than the children who had been told to.

The researchers think that choosing helps children see themselves as "someone who shares". This was a lab study from one research group, and we read the summary and press release rather than the full paper. Still, it is a useful idea: set up chances to choose sharing, rather than always insisting on it.

Does working together make children share more?

It seems to. In a 2011 study, three year olds shared rewards equally when they had earned them together. When the rewards simply turned up, or when each child had worked separately, they were much less likely to share equally.

This was a small lab study. But it suggests a practical idea: do something as a team first, then share what you made together.

Should I reward my child for sharing?

Probably not with prizes. In a study of 20 month olds, toddlers given a toy as a reward for helping went on to help less afterwards than toddlers who were praised or given nothing.

That study was about helping, not sharing, and with very young children. But it matches a wider pattern found with older children too: expected rewards can lower their own interest in an activity. Noticing and naming the choice works better: "You chose to give her a turn. That was kind."

What helps, then?

A few principles that follow from the evidence:

• Expect the gap. Under-7s often know the rule and still keep the bigger piece. That's normal.
• Offer a choice, then notice it. "Would you like to give one to your brother?" If they do, name it.
• Work together, then share. A shared job makes a shared reward feel fair.
• Practise with things that don't matter much. Pegs, crayons or socks, not a favourite toy or sweets.
• Play games with turns. The Harvard Center on the Developing Child recommends card, board and movement games for young children, because they need turn-taking and self-control.

The short version

Most young children know they should share long before they do it. Fair sharing usually arrives around 7 or 8. Until then, choice seems to work better than force, working together makes sharing feel fair, and noticing beats rewarding. Practise little and often with things that don't matter much.

TinyDeposits gives you a simple ten-minute plan for each child, so small moments like these happen on purpose, not by chance.

A summary of published research and guidance for parents, not medical advice. "Linked to" means a connection was found, not proof of cause.