When we go through our school of missions in our sending agency, we have an amazing program for the kids as well. The idea is to prepare the kids for some of the challenges that they might encounter on the mission field. The leadership builds community and unity and identity in the kids by encouraging them to embrace “the MK way” by constantly referring to them as Missionary Kids (MKs). Most kids bloom under this kind of encouragement and thrive in their identity as an MK.
But not everyone. Sometimes kids get “dragged along” to the mission field- or so they perceive it that way. Some kids come out of the MK training and feel displaced and angry. Change is hard. These kids are part of a family that is going to leave everything familiar to them, all creature comforts that they love, and travel to a new world to tell people about Jesus. Some kids feel like, “If Jesus called my parents, then he forgot to talk to me about this decision!” Some kids end up hating Jesus and his stupid Calling. This is hard.
Six months ago I met an angry MK. She was not comfortable in her own adolescent skin and not comfortable in her new school and not comfortable with being called an MK. She had experienced the double whammy of being a teenager AND having too much change in her life all at once. She was not happy. She bristled when anyone tried to show her love. We loved her anyways.
Six months later, our young friend has changed quite a bit. I almost don’t recognize her! Her hair is now her natural color and no longer hanging over her face. She’s incorporating color into her wardrobe… under her black hoodie. But most importantly for me- she smiles. This girl has made close friends both at the missionary kid school and among the missionary families living in Costa Rica. She is now at place where she is comfortable in her own MK skin.
Recently at a gathering of missionary families, our once angry and resentful kid-of-missionary-parents finally showed that she had embraced her identity as a Missionary Kid. She showed a video that she had made of her and her friends laughing and doing silly teenage things. She set it to bouncy, happy music and added cute titles. And the very last screen was the sentence, “This is the MK way.” I got tears in my eyes as we all wildly applauded her creative expression of who she finally decided to be. She had finally grown into her skin and she is happy again.
Monkeys in My Bag 
I’m afraid I’m quite late on this, but I found this post when I searched google for “Angry missionary kids.” Perhaps you weren’t focusing on what it was that that kids were leaving behind in this discussion, but I do think saying “everything familiar to them, all creature comforts that they love” is a painful oversimplification of what children experience in transition.