Unless you were born with overlapping toes, the most likely cause of the problem is continuously wearing shoes of a poor design or those that fit poorly.  There are, however, other causes that bear mentioning. 

The Causes of Overlapping Toes Include

Rheumatoid and psoriatic arthritis can cause deformities in the joints, which can cause the toes to overlap or press on each other.  Any of the joints of the toes and feet can be affected. … Read the Full Article