Before revision: Three-quarter siblings share one parent, while the unshared parents are siblings to each other, for example, if a man has children with two women who are sisters, or a woman has children with a man and his son.
After revision: Three-quarter first-degree relatives share one parent, while the unshared parents are siblings to each other, for example, if a man has children with two women who are sisters, or a woman has children with a man and his son.