Deprived children have significantly lower IQ's than kids from wealthier families, a new study has found.
They compared data on almost 15,000 children and their parents as part of the Twins Early Development Study (Teds), which investigates socio-economic and genetic links to intelligence.
Children were assessed nine times between the ages of two and 16, using a mixture of parent-administered, web and telephone-based tests.
The results, published in the journal Intelligence, revealed that children from wealthier backgrounds with more opportunities scored higher in IQ tests at the age of two, and experienced greater IQ gains over time.
Dr Sophie von Stumm, from Goldsmiths, University of London, who led the study, said: "We've known for some time that children from low socio-economic status (SES) backgrounds perform on average worse on intelligence tests than children from higher SES backgrounds, but the developmental relationship between intelligence and SES had not been previously shown.
"Our research establishes that relationship, highlighting the link between SES and IQ.
"We hope that our findings will drive future research into the specific mechanisms and factors that underpin the link between SES and IQ and thus, contribute to widening the IQ gap."