Varicose veins are caused by a weakening of the valves found in the legs, and often as a person ages these valves become less able to function well. These valves are important in ensuring that blood in the veins moves up towards the heart and does not fall backwards against gravity. Therefore when these valves fail to work well, blood tends to pool in the veins and not enough blood may be returned to the heart.
Causes of varicose veins include:
Standing for long periods of time
Obesity
Family history- if you have a relative who has the condition then you are more likely to have varicose veins.
Gender - the condition is more common in women than men.
Pregnancy and childbirth