By manipulating the genetic structure of human embryos, they could weed out undesired traits, create the blonde haired-blue eyed ideal race that Hitler once dreamed of, or even use the technology 
(they; could weed out; undesired traits) (they; create; the blonde haired-blue eyed ideal race that Hitler once dreamed of) (the blonde haired-blue eyed ideal race; dreamed; T:once) (they; even use; the technology)
they they the blonde haired-blue eyed ideal race they
could weed out create dreamed even use
undesired traits
the blonde haired-blue eyed ideal race that Hitler once dreamed of
T:once
the technology