The beginning of quantum mechanics came from Einstein's paper (1905a) on the photoelectric effect.  The beginning of relativity came with his 1905d paper, and the famous E=mc^2 corollary is in the 1905e paper.  Citations are in this bibliography from Wikipedia:

 

By Albert Einstein

The beginning of genetics came from Mendel's experiments.  His paper:

 

Mendel, G., 1866, Versuche ber Pflanzen-Hybriden. Verh. Naturforsch. Ver. Brnn 4: 3C47 (in English in 1901, J. R. Hortic. Soc. 26: 1C32)