Brothers and sisters who are not related by blood can get married. According to the law, lineal blood relatives and collateral blood relatives within three generations are forbidden to get married. Brothers and sisters who are not related by blood can of course get married if they are not related by blood. However, it should be noted that if brothers and sisters are fictional blood relatives, if they want to get married, they must first dissolve the adoptive relationship with their adoptive parents before they can get married.
The so-called fictional blood relatives refer to relatives who are not related by blood or lineal blood relatives, but whose status is legally recognized as the same as that of blood relatives. Because this blood relationship is not formed naturally, but set by law, it is also called "quasi-blood relationship".
Brothers and sisters are not allowed to get married. According to Article 7 of the Marriage Law, lineal blood relatives and collateral blood relatives within three generations are forbidden to get married, while blood relatives are very close to brothers and sisters. Even children born together have a high probability of deformity or serious diseases. Love between brothers and sisters is inappropriate, but it can't be transformed into love, so we must be rational and sober, otherwise it will easily lead to serious consequences, which will be unfavorable to both sides.
I hope the above content can help you. If in doubt, please consult a professional lawyer.
Legal basis:
Article 1048 of the Civil Code
Lineal blood relatives or collateral blood relatives within three generations are prohibited from getting married.