Darwin was the grandfather of modern evolutionary theories - he figured out the basics, but nowadays the theories are much more accurate and quite different from what Darwin thought. See the entire field of genetics, for example.
Mendel first discovered this, being an active hortonomist and all. The huge effect they have on our lives - we are breeding factories for genes and just how much of our higher level intelligence is based on them we can only guess, they affect our feelings, they most likely make us pay more attention to our parents than our potential companions, etc. etc. - was discovered much later, in early 1900s. Now many biologists focus on genes and amino acids to study life and the forms it takes rather than inaccurate lumps of flesh and slime we know as "living" entities. [see viruses!]