Thanks for your post and welcome. Unfortunately no one knows what causes this condition and with any condition like this there tends to be an enormous amount of speculation about what could be the cause of such a dysfunctional process.
Here is what is known about the leukemia you have been diagnosed with.
Chronic Lymphocytic Leukemia (CLL) is the most common type of leukemia in the western world. The incidence of CLL increases with age, 75% of cases are diagnosed in patients > 60 years old. CLL is twice as common in men. Although the cause is unknown, some cases appear to have a hereditary component. CLL is more common among Jews of Eastern European descent.
Take care and let us know if you have any other questions.