Radio buttons selected on page load - unwanted

I have a form with a couple of radio buttons.
The form is wrapped within a <dialog> element and will be opened only when a button "Back this project" is clicked.

When opened, however, the first radio button is always selected and there should be none selected before a user chooses any.
Is this default browser behavior or?

Also when the form is closed and re-opened, the previous choice is remembered. How can I deselect all radio buttons once the form is re-opened (I know deleting cache is a bad option therefore wouldn't go for that one)

Here's my codepen: https://codepen.io/d8701a/pen/bGJKRWO

Thanks!
CodePend8701a
...
bGJKRWO
Was this page helpful?