Scientists from Cambridge University have found that offspring may inherit altered traits due to their parents' past experiences.
For example, historical incidents of famine have resulted in health effects on the children and grandchildren of individuals who had restricted diets, possibly because of inheritance of altered epigenetic marks.
Epigenetics is a system that turns our genes on and off. The process works by chemical tags, known as epigenetic marks, attaching to DNA and telling a cell to either use or ignore a particular gene.
The most common epigenetic mark is a methyl group. When these groups fasten to DNA through a process called methylation they block the attachment of proteins which normally turn the genes on.
However, it is thought that between each generation the epigenetic marks are erased in cells called primordial gene cells (PGC), the precursors to sperm and eggs. This 'reprogramming' allows all genes to be read afresh for each new person - leaving scientists to question how epigenetic inheritance could occur.
The new study initially discovered how the DNA methylation marks are erased in PGCs, a question that has been under intense investigation over the past 10 years.
The methylation marks are converted to hydroxymethylation which is then progressively diluted out as the cells divide. This process turns out to be remarkably efficient and seems to reset the genes for each new generation.
Understanding the mechanism of epigenetic resetting could be exploited to deal with adult diseases linked with an accumulation of aberrant epigenetic marks, such as cancers, or in 'rejuvenating' aged cells.
However, the researchers, also found that some rare methylation can 'escape' the reprogramming process and can thus be passed on to offspring - revealing how epigenetic inheritance could occur.
This is important because aberrant methylation could accumulate at genes during a lifetime in response to environmental factors, such as chemical exposure or nutrition, and can cause abnormal use of genes, leading to disease.
"Our research demonstrates how genes could retain some memory of their past experiences, revealing that one of the big barriers to the theory of epigenetic inheritance - that epigenetic information is erased between generations - should be reassessed," Dr Jamie Hackett from the University of Cambridge, who led the research, said in a statement.
The study was published in the journal Science.
