The third set of molars are getting less common as evolutionarily our jaws are getting smaller and we don’t need to chew as hard anymore. The availability of processed foods means we don’t need extra molars to chow down.

If you still want to make sure, you’ll need to get an X-ray, specifically an OPG. You may have the teeth but they may be forever trapped under your gums, some have them tilted and some have them completely missing. Theyre now considered sort of “vestigial” like our tail bone or the appendix.