Last week, we had a suspicion that maybe Nathan couldn't smell. Since I have no sense of smell, it seemed prudent to check it out.
We devised a test. One of us would blindfold Nathan while the other held spoons with mustard or ketchup under his nose. He had to tell us which was which.
First round: Nathan is doing great, getting 100% and peeking from under the blindfold.
Second round: Dave holds down the edges of the blindfold so that Nathan can't see. Nathan starts giving us nonsense answers: Ceili, elephants, garbage, etc.
Intermission: explain to Nathan that this is important to us and could have a big impact on his medical life. Also, there will be no screen time until we're satisfied the test has been done correctly.
Third round: Blindfold tamped down. Nathan gets the first two wrong but then the next six right.
Not entirely conclusive, but I'd say it proves he can smell, at least weakly. Pending further evidence, we'll assume that all of his senses are functional and thus cannot be used as an excuse.