The JW doesn't have a "conscience." Rather, he/she has a "bible trained conscience." Since the JWs wrote their own bible, it follows that the JWs actually have a Watchtower trained conscience. For the JW, conscience is just another term for brainwashing.
If JWs actually had consciences, they wouldn't be able to treat others the way they do, especially not their own family and lifelong friends who decide to leave the WTS. And they wouldn't be able to neglect their "worldly" family members. Cats treat their kittens better than JWs treat their families.