Blood is blood, right? Well, yes and no. Human blood is made of the same basic elements, but within that realm there are distinctions that account for four different blood types (further dinstinguished by negative and positive). What makes the four types of blood groups different is their antigens — the immune defense systems — on the surface of the red blood cells.

In 1930, a Japanese professor by the name of Tokeji Furukawa published a paper claiming that the individual blood types — A, B, AB and O — reflected the personalities of those who possessed them. Since then, blood type categorization, “ketsueki-gata,” has become firmly entrenched in Japanese culture. Much like astrological horoscopes, Japanese television and newspapers offer blood type horoscopes, and books that detail the link between blood type and personality are perpetual bestsellers. There are even matchmakers who specialize in finding future spouse based on blood types. But much like astrology, a scientific correlation between blood type and personality remains unproven.

That said, there’s been plenty of research detailing how blood types can reveal patterns of personal health — and that's fascinating in and of itself. It’s thought that different blood types may protect us from different diseases; scientists have been finding links between blood types and illness since the middle of the 20th century. With that in mind, here’s what the science has to say about your blood type. And for fun, we’ve thrown in a little ketsueki-gata as well.

If you have blood type A

Type A only has A antigens on red cells and B antibodies in the plasma; if you have type A blood, you can donate red blood cells to types A and AB.

The makeup of a person’s antigens on red blood cells can determine how much of a certain hormone gets released. If you have type A blood, you're more likely to have higher levels of the stress hormone cortisol in your body, according the National Institutes of Health. There are a number of health risks that are associated with type A blood, such as a 20 percent higher chance of developing stomach cancer compared to types O and B, and a 5 percent increased risk for heart disease compared to those with type O.

In addition, if you have type A blood, you are at higher risk for several types of cancer, such as some forms of pancreatic cancer and leukemia; according to the BBC, you are also more prone to smallpox infections and severe malaria. Ironically, those with type A also have been found to be less magnetic to mosquitoes — so there's reason to rejoice!

According to ketsueki-gata, if you have blood type A, you have some great traits. You are earnest, creative, sensible, reserved, patient and responsible (even if you are also stubborn and tense).

If you have blood type B

If you have type B blood, you only have the B antigens on red cells and A antibodies in the plasma; you can donate red blood cells to those with types B and AB blood.

Those with type B have an 11 percent increase in risk of heart disease over those with type O. A study at Harvard University found that women with AB or B blood have a raised risk of developing ovarian cancer, but if you have type B, it’s not all bad news. Those with type B blood have up to 50,000 times the number of strains of friendly bacteria than people with either type A or O blood, which means all kinds of good things.

And in terms of ketsueki-gata? You can be proud of your passion, active nature, creativity and strength. On the other hand, you’re also selfish, irresponsible, unforgiving and erratic.

If you have blood type AB

Those with AB blood have both A and B antigens on red cells, but neither A nor B antibody in the plasma. If you have AB positive blood, you are universal plasma donor.

People with type AB have been found to have a 23 percent increased risk of heart disease over those with type O blood. Having AB blood may double the liklihood that a pregnant mother will suffer from the blood pressure condition called pre-eclampsia.

One intriguing blood type study published in the journal Neurology found that those with type AB blood were 82 percent more likely to have cognitive difficulties — specifically in areas like memory recall, language and attention — than people with other blood types. The researchers suspect that the clotting protein known as coagulation factor VIII is to blame. “Since factor VIII levels are closely linked to blood type, this may be one causal connection between blood type and cognitive impairment,” said study author Mary Cushman.

When it comes to ketsueki-gata, if you have type AB blood you're cool, controlled, rational and adaptable … and critical, indecisive, forgetful and irresponsible.

If you have blood type O

If you fall into the O blood group, you have neither A nor B antigens on your red cells, but both A and B antibodies in your plasma. O positive is the most common blood type; O negative is the universal donor type, meaning those with this blood type can donate red blood cells to anybody.

For those with type O, it’s a mixed bag. If you have type O, you are more likely to get ulcers — and believe it or not, to rupture your Achilles tendons. You are also at higher risk of cholera. The good news is that people with type O blood are at a lower risk for pancreatic cancer and face a lower risk of dying from malaria than people with other blood groups; that said, if you have type O, you are twice as likely to be a mosquito magnet than those with type A blood.

If you have type O blood, ketsueki-gata suggests that you are confident, self-determined, strong-willed and intuitive; unfortunately, you are also self-centered, cold, unpredictable and potentially a workaholic.

Do you know what your blood type is? Does any of this ring true to you?