Because identical twins start out with identical genes at conception, the study's authors conclude "that the overwhelming contributor to the causation of cancer in the populations of twins that we studied was the environment."
(identical twins; start out; ) (the study's authors; conclude; the overwhelming contributor to the causation of cancer in the populations of twins) (we; studied; was the environment)
identical twins the study's authors we
start out conclude studied
the overwhelming contributor to the causation of cancer in the populations of twins
was the environment