Blood Type Not Reason to Question Paternity

Dear Dr. Dave & Dr. Dee,

A family member and her husband have blood type A and AB, but they have a blood type O baby. I've looked into this, and found that it is impossible for them to have an O child. What do you think?

Signed,

Looking for an answer

Dear Looking for answer,

Using blood type to determine paternity is not very accurate. According to nephrologist, Dr. Michael Linsey, "The ABO/ABH system is actually complex. Web sites that say that certain children are 'impossible' are wrong and may lead people to unjustifiably question their paternity" (Linsey cited in www.science.ca, 2005).

The most accurate method to determine paternity is DNA testing.