You can collect your subscriber's gender by creating a gender custom field for your Subscription Form.
Please note that the custom field is global and will be available across all lists in your account.
Here's how to create a gender custom field:
1. Click on "Custom Fields".
2. Click on "Create New Custom Field"
3.1 Give your custom field a name, example: Gender
3.2 Click on the "Type" dropdown box and select "Multiple choice"
4. Under the "Choices" section, click on the + sign to add another "Label" & "Value" box
4.1 Insert the name of the first "Label" and "Value", example "Male"
4.2 Insert the name of the second "Label" and "Value", example "Female"
4.3 To make this field mandatory, check the box next to "Make this field mandatory to fill in".
To make the first letter of words entered in the field upper case, check the box next to "Fix Cases".
To make this field so that only a unique entry is enter, check the box next to "Force unique value entry".
4.4 Click on "Create Custom Field"
Your Gender custom field has been created, now when you create your subscription form you can add the field to your subscription form to collect your subscribers Gender.