Psychopharmacology, Nuttitional Psych, Hypnotherapy, Counselling
I sort of love the detective work of tracking genetics, ancestry, biochemistry and microbiology most of all.
For instance us Asians tend to lack Lactase (thus lactose intolerant), Aldehyde Dehydrogenase (we get drunk quicker), don't process Vit A as well as Caucasians and we're often born with big teeth on small mandibles (common to have wisdom teeth extractions)...