Relationship Introduction

Different languages have different terms for relationships, and even distinguish different relationships. For instance, Swedish calls your mother’s brother “morbror” and your father’s brother “farbror”, where Danish has “onkel” for both, and English has “uncle”. (In Latin they were “avunculus” and “patruus”.)
On the other hand, English makes some distinctions that other languages do not. Your daughter-in-law and your stepdaughter are both your “belle-fille” in French. And according to the Encyclopædia Britannica, Polynesian languages use the same words for male and female cousins as for brothers and sisters.
Even native English speakers can be confused by some of our relationship terms. A friend asked me to help him figure out what relation he was to his mother’s aunt’s great-grandson. After we had worked that out (see Example 2), he suggested others might be interested. What follows is an expanded and more general form of our discussion.
In English, three sets of terms seem to cause the most difficulty: cousin, in-law, and “half” or “step” relations. Just to make things messy, each of these terms can correctly be used for several different relationships.
Vocabulary: In discussing relationships, phrases like “brother or sister” and “son or daughter” come up again and again. Here are standard gender-neutral terms that I’ll use to shorten the following discussion:
sibling = brother or sister (Some dictionaries call two individuals siblings if they have one or both parents in common. This would include the relationships of half brother and half sister as well as full brother and sister. In this document, I’ll use the word “sibling” in its more restricted meaning: an individual who has the same two parents as you.)
spouse = husband or wife
child = son or daughter (even if an adult)
parent = mother or father