We all know first-born children have it best: they're more likely to be more successful, ambitious and well-qualified.
But a new study has found oldest children also have it hardest in one area: eyesight.
The findings, by Cardiff University's Dr Jeremy Guggenheim, has found while oldest children tend to do better in exams, their eyesight could be far worse than their siblings'. And it could be partly down to their parents pushing them too hard.
"Children with an earlier birth order do relatively better at school owing to parents investing more time, effort and/or resources in educating [them]," Guggenheim wrote.
We all know sitting in front of a screen for too long gives you square eyes (it might sound like an old wives' tale but, according to a 2010 study, it can cause slight myopia).
But the research, of 90,000 individuals aged between 40 and 69, found parents' insistence their oldest stayed indoors during childhood to read or study meant first-borns were 20 per cent more likely to develop severe myopia.
An earlier study of people aged between 15 and 22 in the UK and Israel found short-sightedness was 10 per cent more common in oldest children, compared with their siblings.
"The attenuated effect size after adjusting for educational exposure supports a role for reduced parental investment in education of children with later birth orders in their relative protection from myopia."
Or, to put it concisely: stop pushing your kids so hard. You have been warned...