What are the four extensions of mendel’s law of dominance?

Yes he is correct. These are mendals three laws of motion:

1) two types of “units” or alleles exist for every gene

2) alleles maintain their integrity in each generation (no blending)

3) in the presence of the dominant allele, the recessive allele is hidden, with no contribution to the phenotype.

"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."