When a verb comes after tendency, use the pattern tendency to do something (not “tendency of doing something”):
✗ …the tendency of accepting anything written on a piece of paper
✓ …the tendency to accept anything written on a piece of paper
✗ …the tendency of treating the Holocaust as if it had never happened
✓ …the tendency to treat the Holocaust as if it had never happened
When another noun comes after tendency, the usual preposition is toward (not “of”):
✗ There is a tendency of isolation in modern society.
✓ There is a tendency toward isolation in modern society.