I can still remember my first day at work as a teacher in Ishikawa. After getting the self-introduction out of the way, the conversation changed to questions about my family. As the person talking to me was using words like 妹さん to ask me questions, I assumed that I should reply in a similar way. 妹さんは… I began.
However at this point, I could see that the other teacher was a little uncomfortable. Something about what I was saying was clearly wrong, but I couldn’t for the life of me think what it was. Of course, I now know what the problem was; generally any address ending with -さん is usually used to refer to someone in another group. So while 妹さん is respectful, it is a little too polite to refer to my own sister.
As a rule, you should simply remove -さんto talk about your brother and/or sister. Thus 弟さん and 妹さん become just 弟 and 妹 respectively. The same rule can also be used with uncles and aunts whereby おじさん becomes おじ and おばさん becomes おば.
So far, so easy, right? However, even here there are some pitfalls that the unsuspecting learner can plunge into. For example, when referring to an older sister or older brother, the Japanese respectful forms come out. So if it is someone else’s family, お姉さん and お兄さん are usually used, but the reading changes to 姉 (あね) and 兄 (あに) when referring to your own family. While this change makes things easier to say, it does cause a lot of confusion.
One of the fascinating things about this is that foreign people who marry into a Japanese family are referred to based on the family member that they married and not their own age. Therefore even if your little sister/brother marries a much older person, that person is referred to as a 義理の弟 (little brother-in-law) or 義理の妹 (little sister-in-law) because they are married to your younger brother/sister.
To further complicate things for married learners, when you refer to wives or husbands the words change. If it is your own husband/wife, you may refer to him/her as 夫 or 妻, respectively. If it is someone else’s this is considered too casual, so instead ご主人 or 奥さん are used instead.
Any children that you have with your spouse also have their own rules as one’s own children are 息子 (son) and 娘 (daughter). Intriguingly, 息子さん and 娘さん are both used, but you will also hear 坊ちゃん and お嬢さん used to talk about another person’s family in polite language.
For many learners, referring to one’s parents can be tricky as when referring to other people’s families, Japanese speakers will say お父さん (father) and お母さん (mother) to be respectful. Similarly to 兄 and 姉, this is often considered too formal to use for one’s own parents, so Japanese will often refer to their own fathers as 父 (ちち) and mothers as 母 (はは).
A similar thought process can be seen when talking about grandparents. The speaker’s grandparents are usually addressed as 祖父 and 祖母, whereas other people’s grandparents are called by the more respectful terms お祖父さん and お祖母さん.
The many different words for family members are perfect examples of the Japanese habit of dividing their world into 尊敬 (respectfulness) and 謙譲 (humbleness) and how the words change depending on this. Although these words can be challenging, learners shouldn’t worry about making mistakes too much. I personally got through my first year in Japan despite stumbling over all my addresses and was still able to make myself understood!