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Whether you believe in fate or horoscopes may be determined before you are even born, according to research.

Our personal 'locus of control' – the extent to which we believe we can control events that affect our lives - is partly influenced by the amount of the 'male' hormone testosterone that we are exposed to in the womb, the study found.

An individual is said to have an internal locus of control if they feel that they are in control, or an external one if they feel that the things that happen to them are controlled by external forces.

Written in the stars? Our personal 'locus of control' – the extent to which we believe we can control events - is influenced by the amount of the 'male' hormone testosterone that we are exposed to in the womb

Previous studies have found that women are more likely than men to have an external locus of control, an effect that remains stable across cultures.

For the study, psychologists from Swansea University measured participants' index and ring fingers and worked out the ratio between them - a good indicator of the amount of testosterone a baby has been exposed to in the womb.

The longer the ring finger compared to the index, the smaller the '2D:4D' ratio, which indicates a lot of prenatal testosterone, and is typical in men.

Fingers are a good indicator of the amount of testosterone a baby (stock image of embryo pictured) has been exposed to in the womb

The researchers then assessed the participants' beliefs using the Locus of Control Questionnaire, a standard psychological tool used since the 1960s to measure individual differences in attribution style.

They found that, in women, the smaller the finger ratio on their right hand, the more likely they were to have an internal locus of control, which is more like men.

Writing in the journal Personality and Individual Differences, the researchers said: 'Locus of control is known to be associated with a diverse range of behaviours and outcomes, such as stress and depression, religious belief, and job satisfaction and performance, suggesting that it is an important and far-reaching dimension of an individual's personality.

'The main implication of the findings is that not only may prenatal sex hormones directly affect an individual's locus of control, but that they may also indirectly affect a great number of other behavioural and personality traits that rely on locus of control as an underlying mechanism.'

Study author Professor Phil Reed added: 'The less prenatal testosterone you get as a woman, the more likely you are to have an external locus of control, which is associated with experiencing things like depression and stress – of course, we need to remember there are other influences on this too.'