Unshakeable self belief like that demonstrated by tennis star Andy Murray may be all in the genes, according to new research.

Scientists believe the rock solid self-confidence which often separates life's high achievers from those with similar talent has a genetic basis.

The new belief that this is something people are born with conflicts with previous theories that confidence is based on upbringing and other environmental factors.

So the steely resolve and never-say-die spirit which seems to separate Murray from Britain's previous tennis hope, Tim Henman, may have been inherited, say scientists.

Psychiatrists now say that the ability to perform under pressure may be something some people are born with.

Professor Robert Plomin, of the Institute of Psychiatry, King's College, London, said: 'Everyone has assumed self confidence is a matter of environment.

'Our research shows that it is certainly genetically influenced and that self confidence predicts achievement at school