Purifiers: I got the free probe research in early game. Then I got the bioship research, and luckily I found a few stashes of genetics. I invested all of them in my fleet, and then I sistematically probed all the systems and purified them. By turn 50 the galaxy was empty. Then I got the laboratory that gave +1 score per genetic research. I colonized as many genetic producers as possible, and launched genetic researches until the end of the game :) It was a very lucky run!