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November 15, 2008 |

family tree dna?

dna family tree
baby asked:


do brother and sister have the same dna say there two sister two brother do they all have same dna? also if the family and another family have a baby together what are the results like brother and sister

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2 Responses to “family tree dna?”

  1. F. J Says:

    A brother and sister share (statistically speaking) 50% of the same DNA. Each one gets 23 chromosomes from each parent out of each parent’s 46 chromosomes. So odds are that 50% of your DNA is the same as a sibling’s DNA. Of course, this is simplified to not include crossing-over.

    The only siblings that share 100% identical DNA are identical twins.

  2. guntherbdevil Says:

    Full brothers and sisters have between 1/4 and 1/2 their dna in common (depending on how you calculate that). It’s virtually impossible for 2 siblings to have the identical DNA (except identical twins). In the case of a brother and sister, it’s obvious they have different DNA, because one is a boy and the other a girl! I don’t understand the second question.

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