If the years have not been kind, it may partly be your mother's fault.

Defective genes transmitted from a mother to her offspring appear to play a role in the ageing process, according to new research.

Experiments showed that the mother mutations led to age-related abnormalities in growing mice.

The cuprits are not genes in the cell nucleus, which chiefly determine what we are. They are a separate set of genes in the mitochondria, tiny power plants that generate the chemical energy needed by cells.

Mitochondrial DNA (mDNA) is only inherited from an individual's mother. When it goes badly wrong serious genetic diseases can result, but even mild damage seems to contribute to accelerated ageing.

"If we inherit mDNA with mutations from our mother, we age more quickly," said Professor Nils-Goran Larsson, from the Karolinska Institute in Sweden.

Mitochondrial DNA changes more than DNA in the nucleus, pointed out the researchers, whose findings appear in the journal Nature. When the inherited mutations pile up on top of those that are naturally occurring, a destructive tipping point can be reached, they said.

Other results from the study show that mutated mDNA can lead to developmental brain abnormalities, especially in the hippocampus region which plays a key role in memory.

The hippocampus is especially vulnerable to damage in the early stages of Alzheimer's disease.

"Our findings can shed more light on the ageing process and prove that the mitochondria play a key part in ageing," said Prof Larsson. "They show that it's important to reduce the number of mutations."

Drug treatments, diets or supplements that target mitochondrial function may help to hold back ageing, the scientists suggest.