Is it normal to kiss your siblings on the cheek?
Depends.It depends
Yes, cheek kisses between siblings are normal in many families, though how common they feel depends on your family and culture. The important thing is that everyone involved is comfortable with it.
Plenty of siblings greet each other or show affection with a kiss on the cheek. In some families and cultures, it’s an ordinary hello; in others, even a hug can feel like plenty. There’s no single family rulebook for this stuff.
If it feels natural to both of you, it’s generally just a sweet bit of sibling affection. If one of you doesn’t like it, respect that and stick to another kind of greeting—being family doesn’t mean you have to be touchy.