Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_13555999_1 ( gender VARCHAR, senior_high_school__15_18_yrs_ VARCHAR )

### Question ###
What is the gender of senior high school 26mm?

### Accurate SQL ###

SELECT gender FROM table_13555999_1 WHERE senior_high_school__15_18_yrs_ = "26mm"