We all love a good rags to riches story, but the truth is that poverty never really leaves you. Not only does it have a lasting effect on your health and mental well-being, growing up poor changes you at a genetic level.
A new study demonstrates the extent of poverty's impact on our DNA, revealing that nearly eight percent of our genome can be affected by chemical edits that could stick with you for life.
Researchers from across the US and Canada arrived at this remarkable statistic by conducting a genome-wide analysis on just under 500 participants in the Philippine-based Cebu Longitudinal Health and Nutrition Survey.
Using genetic and survey data taken from women who gave birth in the early 1980s, the team identified a relationship between socio-economic status (SES) and tendency for genes to be modified through a process called epigenetics.
"First, we have known for a long time that SES is a powerful determinant of health, but the underlying mechanisms through which our bodies 'remember' the experiences of poverty are not known," says Northwestern University biological anthropologist Thomas McDade.
The process doesn't change the actual coding of the genes, but is no less physical in terms of its outcome.
Epigenetics involves chemical changes to DNA that prevent or enhance the reading of a sequence. In cases such as this, the precise mechanism referred to as methylation describes the addition of a methyl group to a gene, modifying its transcription.
The phenomenon has attracted increasing focus in research fields over recent years, with studies suggesting everything from receiving affection as an infant to childhood trauma can prompt your body to edit your genes.
As McDade puts it, "There is no nature vs. nurture."
Our early life experiences not only shape our minds, they literally change how our bodies work at a fundamental level. And with signs that epigenetic changes have the potential to be passed on through the generations, any potential cause should be taken seriously.
Applying tailored genetic probes to blood samples taken from the survey's children around their 21st birthday, the researchers identified more than 2,500 sites of methylation affecting 1,537 genes among those identified as being raised in low SES conditions.
Compared with children born into relative wealth, those who became poor later in life didn't show any significant differences.
Since current estimates put the total count of protein-coding genes in our genome at close to 20,000, we're looking at changes to nearly 8 percent of our genes. Further studies could reveal even more changes that weren't evident in this investigation.
Growing up poor is already associated with a significant decline in health for a wide variety of reasons.
Many of the causes are clearly understood. For example, risks associated with differences in diet, access to education, and medical availability can lift chances of disease and poor mental health.
But there are also physiological changes associated with being poor that might not always have convenient explanations, such as chronic inflammation, reduced cell-mediated immunity, and increased insulin resistance, which can lead to health problems.
The study doesn't go so far as to identify precise links between methylated genes and their potential health impacts, but many sites have previously been implicated in the development of important systems related to immunity and neurology.
Further research should help fill in the missing details, demonstrating the extent to which this surprising diversity of epigenetic changes sets up those living in poverty for a lifetime of suffering.
"These are the areas we'll be focusing on to determine if DNA methylation is indeed an important mechanism through which socioeconomic status can leave a lasting molecular imprint on the body, with implications for health later in life," says McDade.
The World Health Organisation estimates some 1.2 billion people across the globe are making their way through life on less than a dollar per day.
Policies and charities that provide health support can only go so far, especially when the consequences of poverty stretch beyond the childhood years.
This research was published in Physical Anthropology.