It might be natural not to use the possessive pronoun in Norwegian but in English it is far more natural to use the possessive pronoun. This type of thing happens a lot in different languages (for example, German "Sie wäscht sich die Hände" or French "Elle se lave les mains" vs English "She washes her hands").
I think it's mostly because europeans consider these types of things already in possessivr, you can't wash someone else's hands (well technicaly you can, but..) or having someone else's head hurting you. Even though in french we'll use the possessive with spare time, probably because it's kinda recent ( I guess peoples before the 20th century didn't think about having free time, while they already knew the words hand and head since a goddam long time...)
English did the same thing until the 1600s. Before that, inversion was the norm: Like you her? Went she? and What saw you? are examples. English still uses inversion for modals and for 'be' when it's the sole verb). You can speak Norwegian --> Can you speak Norwegian? We will rock you --.Will we rock you? The wolf is thirsty --> Is the wolf thirsty? (You should give it a glass of milk.).