In this unexpected scenario, the UFO occupants — despite their obvious technological superiority — are desperate for both human genetic material and the ability to feel human emotions — particularly maternal emotions. Unlikely though it may seem, it is possible that the very survival of these extraterrestrials depends upon their success in absorbing chemical and psychological properties received from human abductees.

p. 190 - Intruders: The Incredible Visitations at Copley Woods (1987)