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General => Ancestral Family Tree DNA Testing => Topic started by: zetlander on Saturday 28 March 15 19:49 GMT (UK)

Title: DNA Test
Post by: zetlander on Saturday 28 March 15 19:49 GMT (UK)

Could a DNA test confirm if my father and his sister were full brother and sister.  They both had the same mother, some uncertainty if they had the same father - both are now dead.  My father had 5 children my aunt 3.  Would DNA from me and DNA from one of my cousins solve this?
Thanks

Title: Re: DNA Test
Post by: Alexander. on Saturday 28 March 15 20:21 GMT (UK)

Hi zetlander,

An autosomal DNA test should solve this for you. The question ultimately is whether you and your cousin are full first cousins or half first cousins (i.e. you share a grandmother but may or may not share the same grandfather).

Full first cousins would be expected to share about 12.5% of their DNA (850 cM). Half-first cousins would share about 6.25% (425 cM).
http://www.isogg.org/wiki/Autosomal_DNA_statistics

While testing yourself and one cousin would probably be sufficient to answer this question, you could be more certain of the relationship by testing your siblings and other cousins as well.

Alexander

Title: Re: DNA Test
Post by: zetlander on Saturday 28 March 15 22:36 GMT (UK)

Thanks Alexander - excellent answer!