Can you tell if there is a parent-child relationship from blood-type?

A newborn`s blood type is unstable.


We receive many messages from clients saying that they are worried that their children have a different blood type from them. Concerned by this, they decided to order a DNA test.

Blood type is determined by examining the presence or absence of certain antigens of red blood cells, but in infants under 1 year old, the number of antigens is only about one third compared to adults.

As it is difficult to determine the blood type of a child less than a year old, many parents choose not to have blood typing done right after a baby is born. It is not uncommon for a child to be typed as one blood type, and then later in adulthood find out at a periodic health check that they are a different blood type.

Do you just want to know the blood type?


It is said that there are enough antigens in the blood for blood typing from the age of 4, so it is best to wait until the baby has grown some before testing for their blood type. However, what most people want to know is not their child`s blood type, but whether there is a biological parent-child relationship.

Of course, it cannot be said that just because a father and child both are blood type A, that they are related biologically. There are more men that are blood type A in the world than can be counted. Furthermore, there have been cases where a child was born with blood type AB to a father of blood type A and a mother of blood type O due to a mutation.

Even though it is possible to get the answers with just a phone call, there are people who have worried over the issue their whole lives, which resulted in more problems coming up later in life. Before DNA testing, there were no other ways to investigate the biological relationships between people, and people suffered the same worries and problems all over the world.

Is it safe to say that there is a biological relationship just because the blood types match when the child is 4 years old?

The answer is NO. Even if the blood type of the child is a plausible result of combining the blood types of the mother and father, the possibility of a mutation cannot be ignored. A biological parent-child relationship is not clear just from looking at blood type.

If you still have concerns, you can choose to have a DNA test


Compared to the DNA testing of 20 years ago, the DNA testing done today is 100 million times more accurate. Asides from standard cheek swab samples, it is now possible to test a variety of non-standard sample types such as cigarette butts or a toothbrush.

A cheek swab is taken by simply rubbing a cotton swab on the inside of the cheek. It causes no pain, even to a newborn baby. Recent technology can test an inner cheek swab sample about 100 times for a DNA test.

For just 2 – 30,000 yen, it is possible to get results and be rid of your worries in just 3 days. Asides from the parent-child relationship, it is possible to determine grandparentage, relationships between siblings, aunts and uncles, and other family relationships. Please note that there are also situations where certain relationships cannot be tested based on who is participating in the test, or what samples are available.

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