He had 10 siblings, but since Joe Jackson's affair he technically has a step sibling. Which makes 11, But he has 10 cause I don't count Joe's affair child.
1. Rebbie Jackson
2. Jackie Jackson
3. Tito Jackson
4. Jermaine Jackson
5. LaToya Jackson
6. Marlon Jackson
7. Brandon Jackson (Marlon’s twin brother who died less than a year of his birth.)
9. Randy Jackson
10. Janet Jackson
(11'ish?) and Joh’Vonnie Jackson if we’re counting the other child conceived from Joseph’s affair.