What causes varicose veins?

Both of my grandmothers have them and my mom and aunt have them. I am 26 years old and I think I am starting to get them. Is it hereditary or was it their sedative lifestyles that caused women in my family to get varicose veins?

I have recently vowed to live a healthier lifestyle by eating good and I work out at the gym 4 days a week. Can I reverse the varicose veins?

Taken from: http://www.medicinenet.com/varicose_vein...
The causes of varicose and spider veins are not entirely understood. In some instances, the absence or weakness of valves in the veins, which prevent the backward flow of blood away from the heart, may cause the poor circulation. In other cases, weaknesses in the vein walls may cause the pooling of the blood. Less commonly, varicose veins are caused by such diseases as phlebitis (inflammation of the veins) or congenital abnormalities of the veins. Venous disease is generally progressive and cannot be prevented entirely. However, in some cases, wearing support hosiery and maintaining normal weight and regular exercise may be beneficial.

Taken from: http://www.webmd.com/skin-problems-and-t...
Some people may be more likely than others to develop varicose veins because of inherited characteristics (genetics) and the aging process. Varicose veins may also result from conditions that increase pressure on the leg veins, such as being overweight or pregnant or having an occupation that requires standing for long periods of time.

All veins have valves in them which help pump the blood back into the heart, with vericose veins these valves become enlarged and the valves do not work properly, so blood pools in these areas enlarging the veins. Vericose veins can be hereditary, and are also caused by the lifestyle (standing for long periods of time, crossing legs while sitting often etc..)