This is my family
The Japanese language has different words for members of the family depending on whether they are your own family, or someone else’s family. Then they also have a different way of talking to members of their own family and a way of talking about members of their own family when they are not present. Amid all this children make short-cuts and parents have their own way of communicating with their own children; that is no different in any other language or culture.
On the left (orange) you see the word as it is used for talking about someone else’s family and on the right (light blue) you see the word as it is used when talking about your own family when they are not present.
Sometimes Japanese use the title ちゃん chan instead of さん san, to show how close they feel to that person. It is a form of endearment.
Men and boys use ぼく boku in informal conversation, meaning ‘I’.
However, when you talk to your own younger brother you would use his name (even if abbreviated) and add くん kun to it. You would never refer to him by his rank, if he is a lower rank. It would be regarded as humiliating. The same you would do when talking to someone else’s younger brother. It is not cool to put someone down, even though you know he is younger.
However, when you talk to your own younger sister you would use her name (even if abbreviated) and add ちゃん chan to it. You would never refer to her by her rank, if she is a lower rank. It would be regarded as humiliating. The same you would do when talking to someone else’s younger sister. It is not cool to put someone down, even though you know she is younger.
We have added another point here (a little related because it is about modesty):
Another point that should be made is that, if you begin to learn Japanese, try very hard to leave out the word わたし watashi or ぼく boku or あなた anata. Sometimes it is essential so as not to confuse people, but in 9 out of 10 cases it is perfectly well understood that the conversation is about you or me. To use those pronouns would be a form of attention seeking; no different from (example):
ME wanting to talk about MY horse in MY meadow when the sun was shining on MY land and MY horse jumped over MY fence and then MY vet came to ME to give ME HIS bill for HIS consultation. It all happened on MY land. So there!
Really annoying and one would think that person does not have many friends.
Therefore introduce yourself as:
スミスです。 (My name) is Smith. or
なまえはスミスです。 (My) name is Smith.
Don’t say:
わたしのなまえはスミスです。
(It really means: “Attention, please! Please note that MY name is Smith!”) Just way too much!
Lami Japan 
