Drop Down List selected Item carry out search using stored proc

 I have stored procedure for searching Database and return results. Passing parameters to stored proc from code behind page.
Now, i have to add a drop down list to the search form with 3 List Items in it.
Male
Female
Both
In the database table(where i need to search in) data is stored as below(of course lot more records exist).
 
Name Male Female John Y N How Can I carry out search by passing the user selected criteria?It should handle either of the ListItems. Thank you
...