Why do living things go to great lengths to increase
their chances of reproduction?

Living things use structural strategies and behavioral strategies that increase their chances of reproduction.

Living things do so to reach the reproduction goal that is to pass genes on to offspring. For example: the pouch of a kangaroo, a frog croaking a mating call,  and colorful petals of flower etcetera helps in increasing mating chances so that their genes can be followed to the generation.

"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."

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.