In many of the studies we've seen researchers look at how much of human behavior is determined by genes and how much by the environment. this is known as the

 The answer is nature vs nurture debate. Our genes (nature) have a direct impact on our phenotype (physical appearance) and other biological traits including personalities. However, the environment (culture, childhood experiences, and etcetera) have an impact on our behaviors. This study of the nature's impact on our behavior is also a realm of epigenetics. This is the study in the changes of gene expression without any changes in the sequence of DNA (genetic material) of the organism. The environment, and age are significant in epigenetics.  Chemical modification of DNA nucleotides such as histone modification, methylation can be influenced by environmental factors.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."

i might be wrong but i think its a. let me know if i’m right and have a good rest of your day!