English Idioms: Family & Relatives — 10 Expressions You Need to Know

Family is one of the richest sources of idiomatic English. Long before anyone coined a phrase for the office or the internet, people were describing their parents, siblings, and relatives with vivid, memorable expressions — and many of those phrases are just as common in a boardroom or classroom today as they are at a family dinner. When someone says a talent runs in the family, or calls a relative the 厄介者, the image does most of the teaching for you. For a look at how idioms show up in other parts of life, see our guides on idioms about love and relationships そして idioms about home and house.

In this week’s idioms guide we look at ten high-frequency expressions about family and relatives, grouped by the kind of relationship they describe — bonds and loyalty, resemblance, secrets, and closeness. For each one you get a clear meaning, the real origin story behind it, and two natural example sentences you can drop straight into a lesson or a conversation.

Why Teach Family Idioms?

Family idioms make excellent teaching material because every student, regardless of age or level, has personal experience to draw on. Ask a class to describe their own 厄介者 relative or explain what runs in their family, and even shy students tend to open up — the topic is universal and emotionally engaging in a way that abstract vocabulary rarely is. These expressions also translate well across cultures, since most languages have their own sayings about blood, resemblance, and loyalty, which opens the door to comparison and discussion.

Beyond the classroom, family idioms appear constantly in everyday English — in conversation, memoirs, sitcoms, and news profiles of public figures. A learner who understands that being someone’s flesh and blood means being their close relative, or that following in your parents’ footsteps means choosing their career path, will follow far more of what they read and hear. Below are ten of the most useful, grouped by theme.

Blood Ties: Idioms About Family Bonds

1. Blood is thicker than water

意味： Family relationships and loyalty matter more than relationships with friends or outsiders.

起源： The phrase, in its modern sense, has been recorded in English since the early 1800s. A popular theory claims the saying originally meant the opposite — that the “blood” of a battlefield oath between comrades was thicker than the “water” of the womb — but etymologists have found no solid documentary evidence for that reversed meaning. What is certain is that by the Victorian era, the phrase had settled firmly into today’s sense: family loyalty outranks every other kind.

例:

• We argue about almost everything, but he’s still my brother — blood is thicker than water.
• She dropped her vacation plans the moment her cousin needed help; in that family, blood is thicker than water.

2. Flesh and blood

意味： One’s own close relative, especially a parent or child; also used to mean “a real, living human being with normal feelings and limits.”

起源： The phrase traces back to biblical language describing kinship in strikingly physical terms — the idea that relatives are literally made of the same body and blood. English absorbed the expression centuries ago as a way to stress a bond too close and too physical to deny. The Merriam-Webster entry traces this same double meaning back through centuries of use.

例:

• I could never abandon him — he’s my own flesh and blood.
• Even after being adopted as a baby, she always wondered about her flesh and blood.

Family Traits and Resemblance

3. Like father, like son

意味： A child behaves, looks, or turns out very similar to a parent (the phrase flexes to “like mother, like daughter” as well).

起源： This proverb has classical roots, appearing in Latin as qualis pater, talis filius, and reflects an observation so old and so universal that versions of it exist in dozens of languages. It was fixed in its current English wording by at least the sixteenth century.

例:

• He fixes every engine himself, exactly like his dad used to — like father, like son.
• Both of them burst into the same corny jokes at parties; like father, like son, I guess.

4. Runs in the family

意味： A trait, talent, illness, or habit appears across many members of the same family, generation after generation.

起源： The image is straightforward: something “runs,” or flows continuously, through a family line the way a river runs through a landscape, carrying a trait from one generation to the next without stopping. English speakers have used this exact phrasing since at least the eighteenth century.

例:

• Musical talent clearly runs in the family; three generations have played piano professionally.
• Bad eyesight runs in my family, so I started wearing glasses when I was seven.

5. The spitting image (of someone)

意味： To look exactly, strikingly like another person, usually a parent, grandparent, or sibling.

起源： Most etymologists, including the Online Etymology Dictionary, trace this back to the older phrase “spit and image,” itself likely a corruption of “spirit and image” — someone who resembles another in spirit as well as appearance. Everyday pronunciation gradually smoothed “spit and image” into “spitting image,” and the modern form was standard by the twentieth century.

例:

• With that same crooked smile, she is the spitting image of her grandmother.
• People stop him on the street constantly because he’s the spitting image of his famous father.

Family Secrets and the Odd One Out

6. The black sheep of the family

意味： The family member who is noticeably different from the rest, often seen as an embarrassment or disappointment by comparison.

起源： In a flock of white sheep, a black lamb stood out instantly, and its dark wool couldn’t be dyed, making it less commercially valuable to farmers. Old folklore also linked a black-coated lamb to bad luck. Together these ideas gave English “the black sheep” as the family member who simply doesn’t fit the mold.

例:

• I’m the 家族の厄介者 — everyone else went into medicine, but I became a chef.
• He’s always been the 厄介者, showing up late to reunions and skipping the family business.

7. Skeletons in the family closet

意味： Hidden, often shameful secrets from a family’s past that relatives would rather keep buried.

起源： The broader idiom “a skeleton in the closet” dates to nineteenth-century England, evoking the darkly humorous image of hidden evidence of past wrongdoing kept out of sight. Applied to a family, it describes long-buried scandals or embarrassments that tend to surface at the worst possible moment — a wedding, a funeral, or a nosy relative’s dinner-table question.

例:

• Every big family has a few skeletons in the closet, and ours is no exception.
• The reporter dug into the senator’s past and found more than one skeleton in the family closet.

Family Closeness and Loyalty

8. A close-knit family

意味： A family whose members are emotionally close, supportive, and spend significant time together.

起源： “Knit” comes from knitting, where individual threads interlock tightly to form one strong piece of fabric. Applied to people, a “close-knit” group is bound together the same way — tightly, and hard to pull apart without unraveling the whole thing.

例:

• Growing up in a close-knit family, we had Sunday dinner together every single week.
• Despite living on three different continents, the siblings remain a close-knit family thanks to daily video calls.

9. Follow in your parents’ footsteps

意味： To take the same job, hobby, or path in life that a parent followed before you.

起源： The image is literal: walking exactly where someone else has already walked, placing your feet in the tracks they left behind in snow or soft ground. English has used this figuratively for centuries to describe following someone’s example, and it became especially common for children who take up a parent’s profession.

例:

• She followed in her mother’s footsteps and became a pediatric nurse.
• Neither twin wanted to follow in their father’s footsteps and take over the family farm.

10. Keep it in the family

意味： To keep money, a business, information, or a decision within the family rather than involving outsiders.

起源： This straightforward idiom reflects the long tradition of family businesses, land, and money being passed down and managed exclusively by relatives, rather than sold or shared outside the bloodline, to preserve wealth, reputation, or privacy.

例:

• When Grandpa retired, he sold the bakery to my aunt just to keep it in the family.
• The divorce was messy, but the siblings agreed to keep it in the family and stay quiet with the press.

Watch: 10 Family Idioms in Action

Want to hear these expressions used naturally by a native speaker? This video walks through family idioms and expressions with clear pronunciation and real examples — a great listening follow-up to today’s lesson.

How to Practice Family Idioms

The fastest way to make these idioms stick is to connect them to real people. Ask students to draw a quick family tree and label it with as many idioms as apply: who is the 厄介者? What trait runs in the family? Is anyone the spitting image of a grandparent? Personalizing the vocabulary turns an abstract phrase into a story learners actually want to tell.

For homework, have students interview a family member and report back using at least three of today’s idioms. This forces natural production rather than passive recognition, which is exactly the skill that turns “knowing” an idiom into being able to use it in a real conversation. Master these ten and you’ll be able to talk about anyone’s family — including your own — with far more color and confidence. If your class enjoyed this set, our idioms about work and ambition guide is a natural follow-up lesson.

情報源

• メリアム・ウェブスター辞典 — idiom definitions and usage notes
• ケンブリッジ辞書 — idiom entries and example sentences
• Online Etymology Dictionary — word and phrase origins

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