From News 24, we read more about the study's results.
Early childhood is a "crucial time for establishing the brain architecture that shape's children's future cognitive, social and emotional well-being", the study said.
"Children growing up in a disadvantaged setting show disproportionate levels of reactivity to stress, and it shows at the level of hormonal studies, neurological brain imaging studies and at the level of epigenetic profiling," said Thomas Boyce, of the University of British Columbia.
The researchers studied data on more than 1 500 individuals born between 1968 and 1975 taken from a 40-year demographic study of US households that measured family income during every year of childhood, educational attainment, what level people reached in their careers, plus crime and health as adults.
They found "striking differences" in how the children's lives turned out as adults, depending on whether they were poor or comfortably well-off before the age of six.
"Compared to children whose families had incomes of at least twice the poverty line during their early childhood, poor children complete two fewer years of schooling, work 451 fewer hours per year, earn less than half as much," the study said.
They also received more than $800 a year more in food stamps as adults, and were more than twice as likely to report poor overall health or high levels of psychological distress, the study said.