If the parents are Type A and Type B and the child is Type O, is it really an impossible combination? Drama ‘Love is Coming’As blood types were used as a subject of suspicion regarding paternity, interest in re-examining the blood type combinations of parents and children also increased.
To start with the conclusion, comparing only the four visible blood types is insufficient. The genes passed on to children vary depending on whether Type A is AA or AO, or Type B is BB or BO. In this article, I will summarize everything from representative combinations to the limitations of paternity testing in one go.
First, looking at the answer, parent blood type combinations are divided as follows.
Based on general ABO inheritance criteria Parents of Type A and Type B can have children of Types A, B, AB, and O.However, to become type O, one must receive one O gene from each parent, such as when the A parents are AO and the B parents are BO.
Conversely, two O-type parents can only produce O-type children, while a marriage between an AB-type and an O-type parent results in only A or B types. This is because to have an AB-type child, one must receive both the A and B genes, whereas O-type parents only pass on the O gene.
The key to blood type combinations is which genes can be passed on to children, rather than the parents' outward appearance.
The reason why results differ even though they are the same Type A and Type B
ABO blood types are determined by the combination of alleles received from one parent. Type A can be summarized as AA or AO, Type B as BB or BO, Type AB as AB, and Type O as OO.
Here, Type A parents do not always pass on only the A gene. If they are AO, they can pass on either A or O, and if they are BO, Type B parents can pass on either B or O.
For example, when AO and BO meet, combinations of A and B, A and O, O and B, and O and O are formed. Accordingly, the child can be Type A, Type B, Type AB, or Type O, but when AA and BB meet, the child can only be Type AB.
The actual genotype cannot be determined as a single type based solely on the parents' blood types.This point is important. Therefore, even among parents of the same Type A blood type, the range of blood types that may appear in their children can differ.
If you organize the possible range of children based on parents' blood types into a table
The table below classifies possible and impossible blood types based on general ABO inheritance principles. 'Possible' means that the corresponding blood type can occur, not that all blood types are born in equal proportions.
If we break down three easily confusing combinations using genes...
Conditions under which a Type O child is possible between Type A and Type B parentsThis occurs when both parents each carry the O gene. In other words, when AO and BO meet, the child can become OO, resulting in Type O. If the Type A parent is AA or the Type B parent is BB, the Type O combination is not formed.
Since both O and O types are OO, the only gene that can be passed on to children is O. Therefore, in general ABO inheritance, children are also OO, meaning they are born only as O type.
The result is clearer when combining AB and O types. Since AB parents transmit A or B and O parents transmit only O, the children become AO or BO, and their phenotypes become A or B, respectively.
Therefore, the idea that AB type can result from a relationship between an AB type and an O type is incorrect. Just because there are AB type parents does not mean that an AB type child is possible in every combination.
‘To distinguish the blood type settings in 'Love Comes' from reality
drama ‘Love is Coming’In this series, situations where the blood types of parents and children do not match are used as a device to raise suspicions about the parent-child relationship. Viewers follow the clues in the scenes by plugging the characters' blood types into a genetic chart.
This setup is a dramatic device based on the basic principles of ABO inheritance. The fact that a specific combination does not conform to general genetic rules can serve as a clue to raise questions, but it alone cannot make a final determination of actual family relationships.
Conversely, just because a blood type combination falls within the possible range does not prove paternity. Blood type serves as a reference to distinguish between possible and difficult cases, while genetic testing is used for actual paternity confirmation.
Blood type compatibility and genetic principles are different stories.
| Parents' blood type | Possible blood types for children | Impossible child blood type |
|---|---|---|
| Type A + Type A | Type A, Type O | Type B, Type AB |
| Type A + Type B | Type A, Type B, Type AB, Type O | doesn't exist |
| Type A + Type AB | Type A, Type B, Type AB | Type O |
| Type A + Type O | Type A, Type O | Type B, Type AB |
| Type B + Type B | Type B, Type O | Type A, Type AB |
| Type B + Type AB | Type A, Type B, Type AB | Type O |
| Type B + Type O | Type B, Type O | Type A, Type AB |
| AB type + AB type | Type A, Type B, Type AB | Type O |
| AB type + O type | Type A, Type B | Type AB, Type O |
| Type O + Type O | Type O | Type A, Type B, Type AB |
When examining blood type combinations, interest often extends to personality descriptions—such as the idea that Type A is cautious and Type B is free—or to romantic compatibility. However, personality traits and love styles based on blood type cannot be regarded as established scientific facts, like the ABO genetic rules.
Blood type inheritance is a biological principle in which the outcome is determined by which alleles are received from parents. On the other hand, romantic tendencies are an area where various factors, such as upbringing, experiences, and relationship styles, interact together, so they cannot be explained solely by the four types of blood.
While blood type clues in dramas can be interesting material for mystery, determining family relationships should be done through genetic testing, not blood type.
To summarize, all four blood types are possible from A and B parents, while only O type is possible from two O parents. If you keep in mind that only A or B types are possible from AB and O parents, you can read most blood type combination charts on your own.