Complex sentence: All of the scientists were adamant that they never coerced Genie and that Genie's mother and her lawyers grossly exaggerated the length of testing--in particular, Curtiss emphatically stated that testing sessions never lasted more than 45 minutes and that sometimes Genie initiated the tests.
Split into simpler sentences: All of the scientists were adamant that they never coerced Genie, and said Genie's mother and her lawyers grossly exaggerated the amount of time they conducted tests. In particular, Curtiss emphatically stated that testing sessions never lasted more than 45 minutes and that sometimes Genie initiated the tests.