Blood types can NOT be used as the sole factor to accurately determine identity of the child’s biological father. Normally, DNA testing or DNA paternity testing can make the accurate determination of the father’s identity, except in cases when there are multiple alleged fathers with identical DNA. Ie. Twins, Tripletts and more. Or there could be a false postive when alleged fathers are closely related and inadequate DNA testing was performed.
However, blood types can be used to determine the biological possibility of fatherhood.
The tables below have been assembled using data provided by the University of Illinois on their Web site.
We can not guarantee the accuracy of the data, but we still feel that these tables are a good guideline for addressing questions of paternity.
| Father’s Blood Type | O | A | B | AB | |||||||||||||
| Mother’s Blood Type | O | A | B | AB | O | A | B | AB | O | A | B | AB | O | A | B | AB | |
| Child’s Blood Type | O | D | D | D | X | D | D | D | X | D | D | D | X | X | X | X | X |
| A | X | D | X | X | D | D | D | D | X | D | X | D | X | D | D | D | |
| B | X | X | D | D | X | X | D | D | D | D | D | D | D | D | D | D | |
| AB | X | X | X | D | X | X | D | D | X | D | X | D | D | D | D | D | |
| D – DNA paternity test is required to accurately determine paternity x – This combination is not genetically possible Table 1 |
Examples:
1. Alleged father1 has type O, mother has type O, the child has type O.
Question: Did the alleged father1 cause the mother’s pregnancy to conceive child with type O blood? Per the chart “D“, maybe or maybe not be the child’s father and that DNA paternity testing is needed to accurately determine the child’s paternity.
2. Alleged father1 has type A, mother has type O, the child has type B.
Question: Did the alleged father1 cause the mother’s pregnancy to conceive child with type B blood? Per the chart “X“, it is not possible for alleged father1 to have caused the mother’s pregnancy nor be the child’s father. An alleged father in this situation would be very wise to obtain legal DNA paternity testing to confirm the child’s paternity, asap. Or risk becoming a paternity fraud victim by signing an a paternity confession or allowing his name to be listed as the child’s father before having paternity test results in hand.