The answer is DNA :) (I think)
So, since what you're wanting is pointers for the Essay, then here:
There are many things that affect your food choice.
Biological determinants: Hunger, appetite, taste, cravings, etc
Economic determinants: Cost, income, availability, etc
Social determinants: Culture, family, peers, meal patterns, what you grew up eating, etc.
Physical determinants: Access, Location, education, cooking skills, time
Phycological determinants: Mood, stress, guilt, etc
Attitudes, religion, beliefs, etc.
All of these can decide what you eat, how you eat, when you eat, and how often you eat.
Is there a picture I should be looking at?
