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Do Only Children Grow Up to Have Only Children?

2026-09-11

Most of what this site has covered so far is about the decision parents make, why they stopped at one, and what that’s like. This one asks a different, less obvious question: what happens to that child’s own idea of family size, twenty or thirty years later?

Growing up without siblings changes what “normal” looks like

A 2025 study in the European Journal of Population used China’s one-child policy as what researchers call a natural experiment. Because the policy assigned only-child status to huge numbers of people somewhat independently of their parents’ actual preferences, it lets researchers isolate the effect of growing up an only child from the effect of choosing to have one, in a way voluntary-only-child populations don’t allow.

The finding: people who grew up as only children wanted, on average, 0.6 to 0.7 fewer children of their own than people who grew up with siblings, and were 60 to 67 percentage points less likely to want two or more (Chen & Gietel-Basten, 2025). This wasn’t just about what people ended up with. It showed up in what they said they wanted, before circumstance had a chance to intervene.

The researchers call this a “low-fertility trap,” not because anything is wrong with wanting a smaller family, but because it suggests family size can propagate across generations through something simpler than genetics or finances: your own childhood quietly resets your sense of what a normal family looks like.

A pattern this site’s readers may already recognize

It’s worth being honest about the limits here. This is a China/one-child-policy population, a context shaped by decades of state policy, not free choice, which makes it a strange population to draw conclusions about voluntary only-child families in the US, UK, or Australia from. The mechanism, that your childhood becomes your reference point, plausibly generalizes; the exact size of the effect probably doesn’t.

That said, a 2019 study using French survey data found a real, if weaker, version of the same pattern in a completely different context: parents’ and children’s family sizes are positively correlated across generations (roughly 0.12 to 0.15), stronger for mothers than fathers, though this correlation has been shrinking over successive birth cohorts, meaning family of origin has less pull on people’s own choices than it used to (Beaujouan & Solaz, 2019). Put together, the two studies tell a consistent, cautious story: family size does seem to echo across generations, but that echo is getting quieter over time as people’s choices become less tied to how they were raised.

What our own poll can’t tell us here

Worth flagging honestly: this site’s 2026 reader poll asked parents why they had one child, not whether they themselves grew up as an only child, so there’s no direct comparison to offer from our own data on this particular question. If you’re a reader who grew up an only child and now has (or is considering) one of your own, Should I Have Another Child? is the piece on this site written most directly for that decision, and it’s a genuinely good candidate for us to eventually ask about in a future poll.

What this doesn’t answer

We went looking for research on a related, narrower question, whether having an only-child parent (as opposed to being one yourself) shapes a grandchild’s closeness to extended family or grandparents, and came up empty. It’s a genuine gap in the published research, not just something we didn’t have time to find. If that’s a question you’re sitting with, it’s one this site can really only answer through your own stories, not a citation.

Sources cited:

  • Chen & Gietel-Basten (2025), “Only Children and Low Family Size Ideals: Did the One-Child Policy Create a ‘Low-Fertility Trap’ in China?” European Journal of Population, 41(1):32
  • Beaujouan & Solaz (2019), “Is the Family Size of Parents and Children Still Related? Revisiting the Cross-Generational Relationship Over the Last Century,” Demography, 56(2), 595–619, note: not independently re-verified against the full text, figures from search-result summaries