Kids nicknames

My elder son we called him "Baobei" and younger one "Xiao Baobei" I feel that it is closer to give them nicknames than just calling their name. When I was young, I had a nickname too. My family called me "Meimei" even though I am the elder daughter whereas my sister do not have a nickname. I am closer to my family as compared to my sister. Even up till now, my family still calls me by my nickname!