Raising them to be chicken killers does not mean they won't still turn out to be big softies.
When I was 7 or 8 years old I was expected to help pull feathers out of recently butchered chickens. I remember distinctly watching roosters run around with no heads after my dad had decapitated them with an axe. I remember the awful smell of the feathers after the chickens were dipped in scalding hot water and the sound of the pressure cooker as Mom attempted to make the meat more tender. Most of the time hens were safe unless they were especially old but my Dad would buy the chicks straight run so we would have extra roosters that would need to be thinned out. I remember being excited whenever new chicks would arrive but it was mingled with sadness because I knew one day in the near future it would mean chicken killing day. As soon as the chicks were old enough for me to tell which ones were males and which ones were females I would avoid the males like the plague trying hard not to get attached to them. I would also never name them if I knew they were going to be food one day. My parents would let me pick a rooster that I wanted to keep, which was kind, but I also felt a little like the grim reaper of the chicken world. I never resented what my parents did but to this day I don't choose to have the stomach for killing what I raise. I do believe it is a choice. If I had to survive by killing my own food, I would, but foodlion is just way convenient and it's easier to to enjoy my food if I haven't spent hours crying over it. When I was little I would rescue drowning earthworms from puddles so my temperament gives me a bit of a disadvantage from my fellow omnivores.
My advice to parents who raise birds for meat:
1) Do not hide your intentions from your children. Make sure they understand which animals will be pets and which will be food so they have a chance to emotionally distance themselves from the food.
2) NEVER and I mean NEVER let them name the animals destined for the dinner table. Names add attachment.
3) Treat the animals you raise for food with the care of a good steward. They may be destined for the crock pot but ensuring they live quality lives until that day will help your children cope with the loss and respect you. Help them to understand that the animals were put here for us and not the other way around but that that also gives us the responsibility of stewarding what we have been given.
You may never turn them into butchers but you can earn their respect and help them cope with the realities of life. I'm still a softie, but my upbringing has made it possible for me to still enjoy fried chicken and respect folks that raise their own meat.