Determining Paternity

What kind of test is done to determine who a child’s father is?

Determining Paternity

Dr. Greene’s Answer:

Determining paternity is now possible even before a baby is born. This is done by comparing DNA molecules — our genetic blueprints. To do this you need a blood sample from both the mother and the potential father (testing without the mother’s blood is possible, but more difficult — and more expensive). You also need a small sample of amniotic fluid (the water that the baby is floating in). Less than 1/4 teaspoon is sufficient for the test. The amniotic fluid may be obtained by a process called amniocentesis. This procedure is performed no earlier than 13 weeks into the pregnancy.

A court order or informed consent of all adults involved is required to proceed with paternity testing.

You will need to wait 3 to 4 long weeks for the results. Waiting for these test results can be a very anxious time. Rush orders take 10 to 15 business days, but cost about $500 extra.

If the test says that the person tested is the father, then he probably is — there is about a 99.8% chance. DNA testing is now legally accepted in determining paternity.

Prenatal Paternity Testing

Prenatal paternity testing can be arranged through a company called Genelex, located in Seattle, Washington. They are very helpful, and can be reached at 1.800.523.6487. The test costs $700, and is usually not covered by insurance.

If you wait until after the baby is born, DNA testing can be arranged through most local blood banks (many of which use Genelex). The blood sample can be obtained at birth. Otherwise, the baby should be at least 2 months old, since a fair amount of blood is needed for the test. In my area, this option costs about $600, and is usually not covered by insurance.

HLA Typing

There is also a less expensive method. For years, the only legally acceptable way to determine paternity was something called Human Leukocyte group A antigen typing, or HLA typing, which looks at the whole complement of proteins found on the surface of white blood cells — and on most cells throughout the body. A person’s HLA type is like her genetic fingerprint. It is how her body determines if an individual cell is a part of her or an invader (a cancer, a virus-infected cell, or foreign tissue). HLA typing technology was first developed in the 1950’s to insure matching in transplant cases. HLA typing is available at blood banks, and although insurance will not cover it for determining paternity, the tests may be obtained for several hundred dollars.

Dr. Alan Greene

Dr. Greene is the founder of DrGreene.com (cited by the AMA as “the pioneer physician Web site”), a practicing pediatrician, father of four, & author of Raising Baby Green & Feeding Baby Green. He appears frequently in the media including such venues as the The New York Times, the TODAY Show, Good Morning America, & the Dr. Oz Show.

  1. Lori Pequeno

    My mother and father are deceased. I believe my mother was ab+ and my father was o- or rh-. My mother kept me away from my father. My aunt and uncle practically raised me. I found out my blood type is b-.
    Was my father my father?

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    • It’s not possible to know for sure based on blood types alone, but this is a possible combination. In other words, your blood types do not give you any reason to believe he is not your father.

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  2. Yvonne

    According to my mother, both she and my father are 0. All my sibling are 0. I, however, am A+. Does it mean there is a problem with regards to them being my biological parents? My mother swears she was only ever with my father.

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    • Two O blood type parents can only have an O blood type child, but often people are mistaken about their blood type. Before you jump to conclusions, you should all be tested again to confirm.

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  3. angela

    can two parents who are o positive blood type have an o positive child?

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    • There is a 93.75% chance that two parents with O+ blood will have a child with O+ blood type.

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  4. Halle

    No one in my family has my blood type. My blood type is O Negative. Is that common or does it mean I am not biologically related to my family.

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  5. Halle

    What does it mean if no one in your family has your blood type. My blood type is O Negative. Is that common or does it mean I am not biologically related to my family.

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  6. liz

    Can a mother with blood type A and AB father have an O blood child?

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  7. Anup Solanki

    Can parents, both blood type o positive, have a child B negative blood group?

    Please tell me.

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  8. jenifer

    Is it possible for a baby to be AB positive while one parent is A negative and other is O positive?

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  9. Sue

    Can a ‘paternity’ test be done on adult children, when one parent has already deceased? I mean, would I be able to use my Uncle’s blood sample (if he were willing), in place of my Dad’s?

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  10. Elaine

    Since Eva was a clone of Adam’s DNA, having his exact same flesh and bone; and blood is manufactured in the bone, how could the three different blood types have evolved? Seems to me it would be a closed repeating loop.

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    • Aladdin

      You are right and the result is eve is not from adams flush she is from heven and each son of adam get a wife from heven becouase its impossible to have brothers marry his sisster in the laws if god and geneticly

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