In his "sweet, sing-song voice, father sang, "it's bye-bye to you, Gabe, in the morning". I think for Jonas it must have been the thing that caused him to make the serious decision to take Gabriel with him when he left the community. Father's statement was ominous because it expressed the truth underlying the lies the people had always been told. Although his voice was made it seem like everything was alright, "bye-bye" to Gabriel meant that in the morning he would be killed, not just "released" to a vague, alternate, positive existence like the people have been led to believe. Because Jonas knows the truth behind the facade of his father's soothing voice, he makes the dangerous decision to kidnap Gabriel and include him in his attempt to escape from the society (Chapter 21).
The reason why it affected him is because when he and the giver watched his father relese the twin he had the same sing song voice saying its bye bye to u little baby while he was killing and putting the baby away
um, i think that it made him wanna take gabe:) dont u think gabe would be really cute!! lol