To talk about DD, we have to first talk about how we first met his family. When we had our children, we had decided that we will try our best to raise them to be trilingual for not other reasons than wanting them to be able to talk to their grand parents. When my kids were little, we found a wonderful family day care ran by a Chinese couple. My kids called them Gung Gung and Ah-po (chinese for grandpa and grandma). Gung Gung and Ah-po spoke Mandarin to my children, thought them to recognize Chinese characters and made wonderful Chinese food for them.
We met DD at Gung-Gung & Ah-po’s place. His parents don’t speak any Chinese. It wasn’t their plan to raise DD as bilingual. They just happened to like the daycare and viewed their son growing up in a Manderin-immersion environment as a wonderful bonus.
DD and MM are 3 months apart and they were babies when they met. Now they are 7 and still are best friends. I remember I always talked to DD at Gung-Gung’s in Chinese whenever I saw him there. He spoke Mandarin as fluent as MM. One day, we were at DD’s house for DD’s birthday party. I started speaking Chinese to DD. He looked at me and told me “No, no, you speak English here. This is an English house. ” He later explained “We only speak Chinese in Gung Gung’s”
I later did some research and found that bi-lingual children, especially littler ones, need to somehow compartmentalized their lives so they don’t get confused. They “trained” themselves to speak to certain adults in one language automatically. My kids see me and would automatically switch to Mandarin. (well, before they went to school anyway). In DD’s case, he decided that languages are also location-based. Now DD is 8 years old and he can easily switch between Chinese and English and is very comfortable speaking to me in Chinese regardless of the location.