4 ms·

This assumes there are no half sisters/brothers in the family.

• b112 3y ago
  It's fair that a half sister is not a sister. At best, you'd expect two half sisters to be a full sister, otherwise, they're a different thing.
  • BurningFrog 3y ago
    I have 1 full sibling and three half siblings, and sometimes like to confuse people by saying I have 2½ siblings.
• lewhoo 3y ago
  Because it's less likely ?