• The Gender field located in the Personal Information portlet in Employee Central-This drop-down menu is a hard-coded picklist and cannot be updated by the end-user.
• As per the KBA, 2093276 - Adding 'Unknown' & 'Undeclared' & 'Others' values to Gender drop-down menu - Employee Central, It is possible to upgrade the system defined picklist Gender so that 3 new values can be selected from the Gender drop-down menu in Employee Central.
• How are country-specific Gender values added to the Gender Field if there is an additional requirement?

• SAP SuccessFactors HXM Suite
• SAP SuccessFactors Employee Central

• To collect country/region-specific information related to genders, a corresponding field can be enabled in the Global Information section with the picklist ID 'gender_XXX', where XXX is a 3-letter ISO country/region code.
• The defined picklist should contain the gender values for the corresponding country/region. The gender field with the corresponding field ID can also be implemented as a customer field.
• Please see the link to the country specific guide below, that Illustrates this :

Local Gender Information

SF, EC, Success factors, Employee Central, Legal Requirement , KBA , LOD-SF-EC-PER-BIO , Biographical Info - Config, Rules, RBP, UI , How To