Re: Why do some people have a better memory than other people?

  This is a very big question.  The quickest answer is that learning and 
memory are complicated tasks requiring the participation of many brain 
regions, neurons, neurotransmitters and proteins.  Genetic (inherited) 
variations in any of one these or in several in different combinations 
leads to differences in ability to learn and remember.  Recent studies 
using transgenic mice (genetically altered mice) have shown a variety of 
effects on learning and memory.  Some transgenic lines show impairments, 
others show improvements depending on which gene was altered.  These 
studies are helping us to understand what must happen in the brain in order 
for learning to occur or a memory to be recalled.  

  But the story is not totally limited to the "nature" side of the nature 
-vs- nurture argument.  Environment also plays an important role.  Factors 
such as nutrition and stress can also influence your ability to learn and 
recall information.  Aging also can alter your ability.  The brain relies 
on glucose (sugar) as its main energy source.  Amino acids and vitamins are 
needed for the brain to make its neurotransmitters (molecules that let 
neurons communicate with each other) and fats in your diet are necessary to 
make myelin, a protective covering on the neurons' axons.  Without 
sufficient energy and nutrients, the neurons can't function well and 
learning can be impaired.  Stress has some interesting effects:  low levels 
of stress seem to help improve learning - like when you are preparing for a 
test - while high (or prolonged) levels of stress seem to impair learning. 
 General arousal also has an effect here - if you don't pay attention or 
care about what you are learning, you won't learn as well or be able to 
recall something as easily as if you paid attention/really wanted to know.