New York, April 8 (IANS): Growing up in a poor and unstable family may not only affect children's psychology, but also their genes, a study has found - throwing new insights into how social conditions in childhood can influence long-term health.

Stressful social environment shorten chromosome-protecting telomeres in kids, the study noted.

Telomeres, repetitive DNA sequences that protect the ends of chromosomes from fraying over time, are shorter in children from poor and unstable homes than in children from more nurturing families, found the researchers.

For the study, researchers examined the DNA of 40 boys from major US cities at age 9 and found that the telomeres of children from harsh home environments were 19 percent shorter than those of children from advantaged backgrounds.

Children's environments were rated on the basis of their mother's level of education; the ratio of a family’s income to needs; harsh parenting; and whether family structure was stable, said Daniel Notterman, a molecular biologist at Pennsylvania State University.

The link between stressful home environments and telomere length is moderated by genetic variants in pathways that process two chemical transmitters in the brain, serotonin and dopamine, the study found.

An imbalance in serotonin levels may cause anxiety and depression.

The study appeared in the journal Proceedings of the National Academy of Sciences.