Dark skinned Norwegian ethnicity

Hello and forgive what may be an ignorant question? I am an American and I do not have contact with my family so I can't ask them further. My father was only partially present in my childhood. He always claimed to be Italian to me but he had a very Norwegian surname (Johansen). I started researching family history and was able to trace his side of the family back several generations to find his father had immigrated to the USA from Oslo. My question is, while I am completely sure that he is/we are Norwegian, he doesn't fit the typical image of a Norwegian person by USA standards. He was a very dark olive skin, with straight black strawlike hair typical more of an Asian person. Myself and my one sibling are both pale but my sister has the same long black hair. Also, in color photos I found, my father's father (grandfather) is even darker than he is, with the same straight black hair. My great grandfather was also very dark skinned. They all have hooded eyelids. My father's mother (grandmother) sometimes claimed to be Romani, but she was batty with dementia and I frankly do not entirely trust her. She is long dead besides so I can't ask her further. Is there an explaination for this? Is it possible they were somehow Italian but living in Norway with Norwegian names, or possible even Romani as my grandma claimed? Is there another ethnic group it could be?