What is the final relationship between the atoms in a covalent bond?

Electronegativity in atoms causally relates to polarity in molecules, as different electronegativities in different components of an asymmetrical molecule cause that molecule to be polar. However, electronegativity differences that are too great lead not to polar molecules, but to ionic bonds. Electronegativity differences also do not lead to polar molecules when they are fully symmetrical because the charges are balanced.

"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."