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Blood Groups - Secrets

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What do Elvis Presley Prince Charles, Al Capone and Charlie Chaplin - not to mention around 26 million people in Britain - have in common? Well, they are all blood group O - the most common blood group in the world. As a donor you'll have been told your blood group - O, A, B or AB. But did you realise what an influence your blood group may have on you?

The famous geneticist Steve Jones's book In the blood describes how researchers have measured the heart rates of people of different blood groups while they listened to music. They found that group As were attracted to harmony, Bs to rhythm, Os to melody and ABs liked all three (especially Bach)!

It’s in the blood
In Japan they attach particular importance to blood groups. On the island of Miyajima, there's a special post 'box with four slots, each marked with a different blood group. For a few yen you can put your hand in and pull out a fortune written according to your group.

So, if you're A you'll discover you're conservative and cooperative, Bs will find out they're eccentric, Os, relaxed, ambitious, but poor on detail, and AB types moody and standoffish! As and Bs should avoid each other as partners, but either would be happy with an AB partner. Os should stick to their own type, and steer clear of Bs.

Japanese couples planning to marry sometimes ask each other their blood group. In business some offices even attempt to get the right blend of blood groups to ensure working harmony!

But why do we have different blood groups at all, and how do we get our particular type?

The science bit
Blood type, like hair, eye or skin colour, is inherited. Everyone inherits two 'blood type' genes one from their mother and one from their father. So you have two blood type genes, the combination of which gives you your blood group. The A and B gene are called 'dominant' genes as they always win over the O gene.

However, neither the A or the B gene are dominant over each other. If your blood group is A, you can only possess one of two combinations of genes A&A or A&O. If your blood group is B you also can have only one of two gene combinations, B&B or B&O. If you are a member of blood group O you can only have two O genes. If your blood group is AB your genes will be A&B.

But why, if O is so easily dominated, is it the most common blood group worldwide? The answer lies in the genes. A study carried out showed approximately seven out of ten people in this country carry at least one O group gene. So the chances of two O group genes being inherited from your parents becomes much higher than inheriting say two B's. That is why in this country, 47% of the population will be a member of the O blood group.

The O group is the oldest of the blood groups. Back in the Stone Age, everyone would have been O and today it's still the most common group in the UK, especially in the North of England. Over in Central and South America and the USA most people are O too. The fact that anyone can receive O blood reflects the fact that all other blood groups are derived from it.

Group A is the second oldest blood group, appearing around 25,000 - 15,000BC, when larger human settlements first appeared as farming developed. You'll find a lot of A in Central and Eastern Europe. It's the commonest group in Norway, Denmark, Austria, Armenia and Japan.

If you're looking for group B, then try the Chinese or Asian communities, where around a quarter of all people share this blood group. It emerged between 15,000 and 10,000BC as tribes migrated from Africa to Europe, Asia and the Americas and mingled with other populations.

The newest and rarest group, AB, only appeared between 1000 and 500 years ago, and is believed to have occurred as a response to the mixing of existing blood groups on a major scale. In Japan, China and Pakistan around 10% of the population boast this rarest of blood groups. Amazing!

Did you know?

  • Only identical twins have exactly the same blood type
  • About 5% of Americans are members of the AB blood group - including John F Kennedy and Marilyn Monroe
  • The Rhesus blood group (Rh) was named after the Rhesus monkey it was first detected in
  • Duelling is legal in Paraguay if both parties are registered blood donors
  • Almost every Peruvian is blood group O
  • Mr Spock's blood type is T negative - Perhaps that's why it's green!
  • Some people believe that you can lose weight by tailoring your diet to suit your blood group

How blood groups are inherited

Here, in a little bit more detail, is the story of how you inherit your blood group.

Everyone’s ABO blood group is controlled by one pair of genes. These may be AA, AB, AO, BO, BB or OO. Many people have difficulties understanding how, say, two group A parents could produce a group O baby.

How it works

The way genes are inherited and the characteristic of the ABO genes can explain how this can happen. Every person inherits two of the ABO genes, one from each parent. These genes determine what the person's blood group will be. The O gene has no blood group substance. It is in fact an absence of either A or B. Therefore, if you inherit the O gene from one parent and the A gene from the other, your blood group will be A. On the other hand, if you inherit O genes from both parents, your blood group will be O. If you inherit the A gene from one parent and the B gene from the other, your blood group will be AB.

You in turn can pass on either one of your two genes to your child. The child's blood group will depend on which of these and which of your partner’s is passed on. If you are group A and have A and O genes and your partner is group B and has the B and O genes,
you could both pass on your O genes to your child, so the child will be group O.

If on the other hand you pass on your A gene and your partner passes on his B gene, the child will be AB! If an A and an O gene combine , the baby will be group A, and if a B and O combine, the baby will be group B. As you can see, several different genetic combinations are possible.

Giving birth

This enquiry from Susan House, in Middlesex, is typical of some questions raised. Susan told us: “I am A negative, as are both my sons, but my daughter is O negative, which your article says is impossible. But I distinctly remember giving birth to her, even if it was almost 33 years ago!”

Well, to be O negative Susan’s daughter must have inherited two O genes – one from each parent. This tells us that, as well as an A gene, Susan must also carry an O gene which she has passed on to her daughter.

Meanwhile, her sons have a different blood type because they inherited a different gene pair – either AO or AA, giving them blood type A. So don’t worry Susan – you know you had your daughter, but science proves it too!

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Blood Groups - Secrets