However, the first cousin's child is not your second cousin, as is often thought to be the case, but your first cousin once removed. The child of the first cousin once removed is your first cousin twice removed, and his child your first cousin three times removed. That second cousin's child is your second cousin once removed, his child your second cousin twice removed, and so on. The third cousin's child is your third cousin once removed, his child your third cousin twice removed.
Siblings have parents in common.
Brothers and sisters are siblings. Stepchild is the child of your spouse by a former marriage. Stepsister or stepbrother is the child of your stepmother or stepfather. Half sister or half brother is the child of your mother and stepfather or of your father and stepmother, or of either parent by a previous marriage. Ancestor is the person from whom you descend directly, such as a grandparent or great-grandparent.