Mitochondrial DNA is inherited along maternal lines.Kate's mother, Kate and Kate's offspring will all have the same m-DNA.
Which in my opinion is precisely why the Portuguese police with Amaral as coordinator of Madeleine's case were so disastrously wrong in using DNA evidence when making Madeleine's parents suspects in her disappearance.
Just as it was proper interpretation of the same DNA evidence by the Portuguese police with Rebelo as coordinator and the Portuguese prosecutors which ensured that there was no case to answer as far as her parents are concerned.
In my opinion it is the non acceptance of the DNA evidence which has festered to condone and allow much of the misinformation in circulation about Madeleine's case.
UK police warned on DNA evidence before McCanns became suspects
Case dossier reveals forensic scientists' doubtsJames Orr, Brendan de Beer and agencies
Mon 4 Aug 2008 19.25 BST
British scientists warned DNA tests on a sample from Kate and Gerry McCanns' hire car were inconclusive just days before they were made suspects, police files have revealed.
Forensic experts described how it was impossible to conclude whether swabbed bodily fluid taken from the vehicle's boot came from the couple's missing daughter Madeleine.
Despite the results from the Forensic Science Service (FSS), Portuguese detectives went on to name the McCanns "arguidos", or formal suspects in the case just four days later.
Significantly, officials even chose to cite DNA evidence as grounds for their suspicions.
Today's revelation came as a vast dossier detailing investigations by the Portuguese police into the disappearance of three-year-old Madeleine was made public.
More than 11,000 pages of evidence were released to journalists two weeks after authorities took the decision to close the case into the missing toddler.
The documents include every witness statement and every lead followed up by detectives working on the inquiry since Madeleine's abduction on May 3 last year.
Transcripts of police interviews with the girl's parents Kate and Gerry, as well as British ex-pat Robert Murat, are also incorporated within the text.
Among the files released is one email written by Mr John Lowe, of the FSS, to Detective Superintendent Stuart Prior, head of the British side of the investigation.
In it the scientist reported that a sample from the boot of the McCanns' Renault Scenic hire car, which they rented 24 days after Madeleine went missing, contained 15 out of 19 of the young girl's DNA components.
But he cautioned the result saying "In my opinion ... this result is too complex for meaningful interpretation or inclusion."
Lowe wrote: "Let's look at the question that is being asked: 'Is there DNA from Madeleine on the swab?'
"It would be very simple to say 'yes' simply because of the number of components within the result that are also in her reference sample.
"What we need to consider, as scientists, is whether the match is genuine - because Madeleine has deposited DNA as a result of being in the car or whether Madeleine merely appears to match the result by chance."
The expert also noted that the components of the missing girl's DNA profile were not unique to her - in fact some of them were present among FSS scientists, including himself.
He concluded: "We cannot answer the question: is the match genuine, or is it a chance match."
Earlier today, the McCann's spokesman Clarence Mitchell said the couple would not be giving "a running commentary" on their legal team's trawl through the files.
The pair, both 40, were formally given access to the evidence last week and are desperately hoping it contains missed clues which could help lead them to their daughter.
"The Portuguese attorney general, in his recent statement, made it very clear indeed that there's absolutely no evidence of any wrongdoing by Kate and Gerry in any way, shape or form and journalists should bear that in mind when they examine the police files," Mitchell said.
"A lot of this is historical detail drafted by officers who failed to find Madeleine and who quite wrongfully were going down inaccurate lines of supposition and assumption. We will not be commenting on any of this.
"All that matters is the search for Madeleine. Kate and Gerry's lawyers are continuing to examine all of the information in minute detail and where anything that is relevant to finding Madeleine needs to be done it will be."
The files relating to the extensive inquiry, which lasted more than 14 months, were made public shortly after 4pm this afternoon.
DVDs containing the documents were handed out to around 50 waiting reporters inside the public prosecutor's office in the Algarve town of Portimao.
Until now Portugal's strict "segredo de justica" - or secrecy of justice - laws have limited the flow of information about the Madeleine inquiry.
The legislation is supposed to ban anyone linked to an ongoing police investigation from speaking about it, but did not stop a series of leaks to Portuguese newspapers.
The McCanns repeatedly complained about restricted information being made public, and the couple believe there was a concerted smear campaign against them.
Madeleine was nearly four when she vanished from her family's holiday apartment in Praia da Luz on May 3 last year as her parents dined with friends nearby.
Despite a huge police investigation and massive coverage in the Portuguese and British media, she has not been found.
Last month, Portuguese prosecutors announced they were shelving the case, although it can be reopened if credible new evidence comes to light.
At the same time the McCanns, from Rothley, Leicestershire, and Algarve resident Robert Murat were told they were no longer suspects in Madeleine's disappearance.
https://www.theguardian.com/uk/2008/aug/04/madeleinemccann.portugal
