NO they are not. It may be a fun idea for a fanfiction but Pein and Sakura are not brother and Sister, if they were because you are either born with Rinnegan or earn it from many years of eteranl Mangekyo Sharingan, she would also most likely have the Rinnegan, or at least stick around Pein.
pein ain't got a family.
Pein is a boy from the rain village HE IS NO WAY RELATED TO NARUTO
Neither but they did have the same sensei.
he woz on Holiday with hinata's sister, Hanabi.
i think he is because if you go to the naruto info sights and look up pein it will say he is related to him.
he did have brother and sister he had two sister and he had 1 brother
Niece is to nephew as sister is to brother.
She has 1 sister, a step-sister, a step-brother, a half-sister and a half-brother
he has one brother one sister
You don't call your brother's sister your aunt. Your brother's sister is your sister, or you. Your aunt is the sister of your mother or father.
You are not related to your sister's husband's brother. However, her husband is your brother-in-law and his brother is your sister's brother-in-law.