How many younger siblings does Justin Bieber have?

Explanation

Justin's mother is called Patricia Malette, but everyone just says 'Pattie'. Her parents are called Bruce og Diana Dale. Bruce Dale is not Justin's biological granddad, he married Justin's grandmother when Justin was two years old, at which point Justin's mother also gained two new step siblings. Justin's father is called Jeremy Jack Bieber and he has two more kids beyond Justin: Jazmyn and Jaxon. There are many people in Justin's family and sometimes it's all a bit complicated, though it doesn't really play a role, according to Justin.