How can know if a form has a parent or not, in a view?

The fast answer is:

{{ form.parent }}

but if the form has a child called parent the above statement always return a result, even when they do not have a real parent.

then the only way to know if has a real parent is something like:

{% set hasParent = (form.parent is not null and (not form.offsetExists('parent') or form.parent != form.offsetGet('parent'))) %}

I'm missing something?

a method hasParent() is needed in the FormView to avoid the \ArrayAccess.