I have a sister one year younger than me and she refers to herself as the black sheep and me the golden child.
In reality she was a defiant little brat growing up who did nothing she was told and was always in trouble I think the polite word was spirited and I wasn't like that.
I got fed up with always having to tidy our room because she refused and tidying up after myself while she refused point blank to do anything.
I wasn't overly good, I just wasn't deliberately rude and disrespectful and as a result have a close relationship with my parents while my sister who has a chip on her shoulder has cut me and our parents off believing they were toxic and I was their favourite.
I think I was probably just easier rather than favourite where she was hard work but equally loved.