The answer to your question is


As you get older many nutritional dilemmas start to pop up, such as loss of appetite, depression, menopause/prostate problems, heart disease, less taste, etc. All of these affect their nutrition and put them at risk for deficiencies.
I hope this helps you!
A combination of genetics and environment.
Physical Appearance I would say because what you look like helps people understand you a bit but doesnt totally describe who you are.