A study of hundreds of female twins found those deemed working class - employed in a manual, unskilled job - can expect to age significantly faster than their middle-class peers. It could reduce life expectancy by seven years.
And moving into the working class through marriage could have an even bigger impact, adding nine years to a woman's biological age.
The association between the rate at which people age and the social class they belong to cannot adequately be explained by low income, poor education or risk factors known to afflict lower socioeconomic groups most, such as smoking, obesity, lack of exercise and bad diet.
However, stress may be the key, the researchers believe. People from lower social backgrounds are more likely to feel insecure, it is claimed. The stress this causes is thought to inflict cellular damage that accelerates ageing. The findings, soon to appear in the journal Aging Cell, are the latest to emerge from the twin research unit at London's St Thomas's Hospital.
Working with colleagues in the US, the researchers, led by Professor Tim Spector, focused on 1,552 British women aged 18 to 75, made up of identical and non-identical twins.
The women were split into different socioeconomic groups based on their occupations, while scientists went on to examine their chromosomes - the coiled bundles of DNA in every cell that contain genes.
What they were most interested in was the telomeres - the protective caps on chromosomes that act like the ends of shoelaces to prevent them fraying and suffering damage.
Scientists believe that telomere-shortening is a key marker for biological ageing, where those with shorter telomeres are "older" than those with longer telomeres, even if in years they are the same age.
In the twins study, researchers found striking differences in the length of telomeres between women from working-class and white-collar backgrounds.
The women from the manual group appeared to have telomeres on average about seven years shorter compared to women in the white-collar group. This suggested that they were seven years "older" than the non-manual group, despite being born at the same time.
"We're talking about a seven-year difference in telomere loss between people of the same age, the same body-mass index, and the same smoking and exercise status, who happen to be in a manual or a non-manual job," Prof Spector said.
The study looked in more detail at the telomere lengths of 17 pairs of twins who started life in the same social class but then separated, with one twin moving "up" the scale and the other moving "down", generally as a result of marriage.
In 12 cases, moving to a new socioeconomic group had an even bigger impact on telomere shortening - with a difference of nine years between social groups in women with an average age of 47.