Why do I not have a static checkbox?

This is probably a very beginner question, but I can’t figure out why my inspector looks different than everyone else’s. All I want to do is mark an object as static, but the checkbox that appears in all the tutorials isn’t in mine. This is what mine shows:174912-inspector-issue.png

AH! You’re absolutely right. One of my custom editor scripts was the culprit.
I changed

[CustomEditor(typeof(GameObject))]

to

[CustomEditor(typeof(MyCustomClass))]