Can brothers marry sisters?
A double cousinship occurs only when a set of siblings marries another set of siblings and both have children. This could be two sisters marrying two brothers. In your case, this is a brother and sister marrying a sister and brother. Double cousins actually share the same gene pool as siblings.
Can you marry your sister in Alabama?
No, Alabama does not allow legal marriage between siblings. Based on the wording of the law, it would seem that “siblings” applies to both those related by birth/blood and adopted children as well.
What is it called when you marry your sister?
Incest /ˈɪnsɛst/ is human sexual activity between family members or close relatives. This typically includes sexual activity between people in consanguinity (blood relations), and sometimes those related by affinity (marriage or stepfamily), adoption, clan, or lineage.