DNA Doesn't Decide Everything in Children's Genes

DNA molecule
The study proves for the first time that DNA is not solely responsible for what genetic material is passed on to children, April 6, 2015. Pixabay/ used under Creative Commons licence.

Genes inherited by children from their parents are not completely determined by DNA and could be partially determined by factors such as diet and stress, new research has found.

Researchers at the University of Edinburgh found some characteristics are determined by histones, the protein spools found in cells which DNA strands wrap around to form the characteristic double helix.

The study, published in the journal Science, is the first time DNA - the molecules containing the biological instructions for cell reproduction - has been shown to be not solely responsible for what genetic material is passed on from parents to children.

It opens up the possibility that environmental factors could affect which genes get passed on from parents to children, though the researchers stress that further studies are necessary in this regard.

Professor Robin Allshire, who led the study, described the findings as "a holy grail in the field".

"We've shown without doubt that changes in the histone spools that make up chromosomes can be copied and passed through generations," said Allshire. "Our finding settles the idea that inherited traits can be epigenetic, meaning that they are not solely down to changes in a gene's DNA."

The researchers tested the impact of histones upon the transfer of genetic material by using yeast molecules, which have similar gene control mechanisms to human cells. The scientists introduced changes to the histone proteins, causing it to switch off nearby genes, and the effect was passed on when the yeast reproduced.

Since environmental factors can cause adaptations to histones and affect which genes are switched on or off in the DNA, it is possible these same factors could influence which genes are inherited by children. However, Allshire notes that more research is required to establish the effect of such factors.

"There is some evidence and suggestion that perhaps these traits can be passed through to the next generation but if it does occur at all it's likely to be an exception," says Allshire.

He adds that human gametes, or sperm and egg cells, contain robust mechanisms to iron out any environmentally-induced changes in histones.

DNA, or deoxyribonucleic acid, is wrapped tightly around histone proteins to fit within the cell nucleus. Many histones combine together to form chromatin, which in turn is further condensed to form chromosomes. Each human cell has 23 pairs of chromosomes.