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Dr. Charogat
Dr. Charogat, Doctor
Category: Medical
Satisfied Customers: 1803
Experience:  Licensed in both NYS and NJ with experience in surgery and medicine.
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if a dna test is done from 2 brothers and the child is one

Resolved Question:

hi if a dna test is done from 2 brothers and the child is one brothers then would the dna for both these brothers not be positive as they hold the same genes
Submitted: 2 years ago.
Category: Medical
Expert:  Dr. Charogat replied 2 years ago.
Dr. Charogat :

Hi, and thank you for coming here with your question.

Dr. Charogat :

The DNA from two brothers will likely have SOME of the same genes, but different in others.

Dr. Charogat :

Each parent has 2 copies of each gene. These two copies are often NOT alike.

Dr. Charogat :

Each parent gives 1 of the two copies to a child. Because they each have 2 unlike genes they can give either one.

Customer:

so would I expect the dna to be positive and the one with the higher percentage is the father

Dr. Charogat :

No. It is all about statistics.

Dr. Charogat :

It might be more likely that they will have some of the same genes, but that is not for sure.

Dr. Charogat :

ie. When they test to see who a parent is they test BOTH parents (usually).

Customer:

so when the dna is being done wil the lab send me the details of the result and one should be negative and one positive

Dr. Charogat :

No. They should both be mixed.

Dr. Charogat :

There are some specific markers. For example blood type.

Customer:

how wil I know whose the father then

Dr. Charogat :

You can try a genetic test of the blood, but unless there are very different results you will still not know.

Dr. Charogat :

Here's an example

Customer:

thanks

Dr. Charogat :

If a child is born to a mother with type A (also called AO) blood, and a father who is the same blood type, then if the child has any Type B blood in him it would show that one of these was not the correct parent

Dr. Charogat :

Because the B would have to come from somewhere.

Dr. Charogat :

Two brother would have a high chance of having the same blood type - and therefore it would not tell which brother the child belongs to.

Dr. Charogat :

Does this help?

Customer:

thank you

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