Apart from anything else, any family tree is subject to that old adage: 'Mummy's baby, Daddy's maybe'.
Sorry but DNA clouds even that assumption check out chimerism and the cases where mummy hasn't been mummy. 
Thankfully further research rectified the situation
Cheers
Guy
But grandma and grandpa are still grandma and grandpa if the parent of their grandchild is a chimera.
Which is why I wrote "DNA clouds even that assumption" rather than DNA clouds disproves that assumption.
The fact that a person can be born with two different types of DNA within their body makes simple statements of fact more complicated.
In possibly the most well know case of chimerism Lydia Fairchild her case was only proved because a court required a test to be carried out at the time of birth of a subsequent child.
However what would happen if it was a father claiming paternity rights for a child, a court could not test his sperm at the time of conception.
As it happens at least one man (in 2014) has been proven to be the father of a child after being discounted by DNA testing previously.
As with Lydia Fairchild it was proved that he was a genetic chimera and that he could indeed be the father of the child he claimed was his.
As the science of DNA matures more data will be generated which may confirm or may disprove many of the assumptions made during this period of infancy.
Science develops through data testing the predictions laid out by the hypothesis, at this stage in the game the science of DNA is still gathering data to test the predictions.
Cheers
Guy
