Why does Sheila stare at the Inspector “wonderingly and dubiously”?

"....because she's already figured out that Eric is (was) the beby's father.

Sheila stares at the Inspector 'wonderingly and dubiously' because the way he makes them confess and feel is strange and no one has ever told her that the way she is livng is wrong. Sheila looks up to the Inspector like a chid with their favourite celebrity, he has taught her things that her narcassistic parents could'nt teach her, he taught her about morality and social reponsibilty something that Sheila will never forget.

because she is a joke and her family is a joke aswelll...

:)