Wive's tale. I agree with dr. Schwartz, getting varicose veins from crossing your legs is a wive's tale.
Yes and No. It is actually a bit of a wive's tale that crossing your legs causes varicose veins. The real risk factor is if your legs are dependent, either sitting or standing, for long periods of time. This creates venous pooling, and venous hypertension, which eventually causes the varicosities. Try to get up and move frequently, elevate your legs if possible, and most importantly use compression stockings.
Prolonged sitting. Prlonged sitting and standing increases venous hypertension in legs with heredity genetics; use support stockings.