Is it possible to have only one wisdom tooth?

YES!!!: You can have none, one, two, three, four, or more! i once removed 6 on one patient!

Thanks for asking!: Yes. Congenitally missing ( hypodontia) teeth are not rare. But missing 6 or more teeth is rare and diagnosable as oligadontia and, may be associated with syndroms.

Yes: Yes. Some have 4, some 3 some 2 and some none.

Erupted or not?: I'm not sure if you mean ever develop or erupt into you mouth. Not all wisdom teeth develop and not all wisdom teeth erupt into the mouth. 4? 3? 2? 1/? None? I have had patients with extra (5th) supernumerary wisdom tooth. Genes and luck when you have less than four develop.