Different people, different diets

juliafromrf

I have been wondering about this for a long, long time. Excuse me if a thread on this topic already exists, I couldn't find anything through the search function.

So what I would really like to know is how different people really are concerning their macronutrient intake, their preferences and "needs" for certain foods.
I've observed preferences for certain types of food in different people. Some "naturally" had a very low carb, but extremely high protein intake and vice versa. What I would like to know is if these differences in diets are only caused by habits and what people learn from their parents in their childhood, or if their body "craves" one macronutrient more than the other (and therefore needs more of it)? The same questions also applies for certain foods/types of food.

For example:
When I was 6 years old, I stopped eating meat altogether. It was my personal decision as I was extremely disgusted by meat products (the taste, not the killing) and definitely not induced by my parents.
What does that mean? That my body doesn't need meat, or that meat could even "harm" my body? Or something else?

Of course, I am aware that everybody IS different. I'm just curious as to HOW different we are and how many of our differences are only based on habits and behaviour we adopted when we were little. I also find it interesting that some people can adapt to a new diet extremely fast, while others desperately fail. I just can't believe that it's only lack of willpower in every case.
Thanks in advance for your replies and please excuse any grammar mistakes and lacking coherence, English is unfortunately not my first language. I hope I've made myself clear though.