Blood type personality · For fun
Blood type personality: what Types A, B, O and AB are said to be like
In Japan and Korea, "Type A is meticulous, Type B goes their own way" is as familiar as a horoscope. Blood type personality theory holds that a person’s ABO blood type shapes their character; it began in Japan and has been a favorite talking point across East Asia ever since.
This page gathers how the four types are usually described, where the idea came from and what research has actually found. The short version: it makes for fun conversation, but there is no basis for using it to judge anyone.
The four types, as they are usually described
Keywords that come up again and again in blood-type lore. Select a type for its full portrait: personality, love, work and how to get along.
Type A
Genotype AA or AO
Careful · considerate · responsible
Pictured as someone who plans ahead and keeps promises, with a sharp eye for how others feel.
Read about Type AType B
Genotype BB or BO
Curious · frank · independent
Pictured as a free spirit who dives deep into what interests them and does not hide likes or dislikes.
Read about Type BType O
Genotype OO
Generous · decisive · sociable
Pictured as the steady one who gathers people and leads, seeing the big picture and deciding without fuss.
Read about Type OType AB
Genotype AB
Rational · original · reserved
Pictured as someone who steps back to weigh things up, warm with others yet guarding their own space.
Read about Type AB
Where the idea came from
That human blood falls into groups such as A, B and O was first shown in 1901 by the Austrian physician Karl Landsteiner. The discovery opened the way to safe transfusions, and before long people began trying to link blood groups to temperament as well.
The best-known starting point for the personality idea is a 1927 paper by the Japanese educator Takeji Furukawa, "A Study of Temperament through Blood Type". It rested on small surveys of people around him, drew wide interest for a time, and faded in the 1930s once later studies failed to reproduce its results and critics pushed back.
The idea returned to popular culture through Masahiko Nomi, a former radio and TV writer whose 1971 book on blood type and compatibility became a bestseller. Japan went through a blood type boom in the 1970s and 1980s, with magazines and television running special features on the four types.
Japanese books and TV carried the idea to Korea in the 1980s and 1990s, and in the 2000s, with the spread of the internet, posts about each type’s dating style and compatibility became hugely popular. It remains a common icebreaker there, though many say MBTI has since taken over much of that role.
What research says
Blood type personality is a long-loved piece of popular culture. But large surveys in several countries, including a 2014 study analyzing the answers of more than 10,000 people in Japan and the United States, have found no meaningful link between ABO blood type and personality. If you would like to look at your current tendencies through your own answers, try the tests below. That does not mean their results connect to your blood type.
So why does it feel so accurate?
The tendency to accept vague descriptions that fit almost anyone as being "about me" is called the Barnum effect. A line such as "usually calm, but sometimes sensitive" will make most people nod, whatever blood type it is attached to.
People also remember moments that fit what they already believe and forget the ones that do not. Some research has found that people who hear a lot about blood types are more likely to describe themselves in line with their type’s image, so the belief can end up producing the resemblance.
Children’s blood types from their parents’ types
A person’s ABO type is set by two genes, one from each parent. A and B both show when they occur together (Type AB), while O is hidden whenever it is paired with A or B. The chart below is calculated from that textbook rule.
| Parents | Possible child types |
|---|---|
| A×A | Type A · Type O |
| A×B | Type A · Type B · Type O · Type AB |
| A×O | Type A · Type O |
| A×AB | Type A · Type B · Type AB |
| B×B | Type B · Type O |
| B×O | Type B · Type O |
| B×AB | Type A · Type B · Type AB |
| O×O | Type O |
| O×AB | Type A · Type B |
| AB×AB | Type A · Type B · Type AB |
Very rare cases such as cis-AB and the Bombay phenotype do not follow this rule, so a result that differs from the chart is no proof about family relationships. A medical test, or donating blood, will tell you your type accurately.
Don’t judge people by blood type
Blood type talk is fun when it stays light. In Japan, though, the problem grew serious enough to earn its own word, "bura-hara" or blood-type harassment, for teasing or excluding people over their type, and unfair treatment in hiring and relationships has been reported as a social issue. In 2004 Japan’s broadcasting ethics body asked TV stations to make sure blood type programs did not encourage prejudice.
Remarks like "Oh, you’re Type B" or "AB, no wonder" can hurt even as jokes. Nobody chooses their blood type, and it does not decide who they are. When you meet someone new, listen to what they tell you about themselves instead.
Blood type compatibility: ten pairings
Matching the four types with each other, same-type pairs included, gives ten combinations. All ten are gathered on one page, each with how lore pictures it and a tip for getting along.
See blood type compatibilityPersonality stories for fun
Western zodiac signs, sorted by birthday, are another long-loved way of talking about personality. Compare them lightly, alongside the tests that look at your current tendencies through your own answers.
Blood type personality: frequently asked questions
Can blood type tell you someone’s personality?
No, there is no scientific evidence that it can. Studies of thousands to more than ten thousand people in Japan, the United States and elsewhere have found next to no personality differences between blood types. Enjoy blood type lore as conversation, and if you are curious about your tendencies, try a questionnaire-based personality test.
Where and when did blood type personality theory begin?
It began in Japan with a 1927 paper by Takeji Furukawa. After fading in the 1930s, it boomed in Japan in the 1970s thanks to Masahiko Nomi’s books, and later spread to Korea and the rest of East Asia.
Which blood type is most common in Japan and Korea?
Type A is the most common in both. In Japan it is about four in ten people, followed by O, B and then AB at about one in ten; in Korea A is about a third, O and B are close behind, and AB is again about one in ten.
If one parent is Type A and the other Type B, what type can their child be?
Their child can be any of the four types: A, B, O or AB. If the parents carry the genotypes AO and BO, every combination of A, B and O can be passed on. Check other combinations in the parents’ chart above.
Is blood type compatibility reliable?
No, blood type compatibility has no scientific basis either. How two people get on depends far more on how they talk and treat each other than on blood type. Enjoy compatibility charts as a light way to start a conversation.
This page reads blood type personality lore as culture and entertainment. Each blood type is shared by a large part of the population, and blood type cannot settle anyone’s personality or relationships. Please do not tease or discriminate against anyone because of their blood type.
How to use this content
- This page is reference content for self-understanding and light interpretation, not a diagnostic or evaluative tool.
- It should not replace medical, legal, financial, or hiring decisions, and important choices need stronger evidence than a self-test.
- Use the result for reflection or entertainment only, and seek professional support first when distress or risk is involved.