How to allow gender other than Male/Female on People Form

I have read this Oracle support note. How to Allow Employees to Identify Gender as Other than Male or Female--US Legislation only (Doc ID 2550119.1)

We are located in California only. When employees are hired, it is not required to provide the gender or can choose option other than Male/Female. The problem is that the Oracle People form is required to put either Male or Female for employee record. It does not allow us to save the employee People form with "Unknown". We can use the EIT - State Level US Gender Preferences. However, the People form must still select Male or Female.