Thank you so much for that. I now feel vaguely able to explain this to someone else.
But how many Markers does any one person's DNA actually have? Or can it vary?
If you mean bits of genetic code, rather a lot...
https://en.wikipedia.org/wiki/Human_genomeI didn't understand the Lowe report, either, when I first read it. Lowe actually talks about "components", which are the alleles.
I'm not a scientist, but I was intrigued enough to try to discover what people were talking about. It was obvious that they were getting muddled, but I wasn't sure why.
Anyway, that is just my understanding of the difference between alleles and markers in the context of the forensic nuclear DNA tests.
To understand bootgate, perhaps the easiest thing is to think of a Venn diagram, something like this:
That only has 3 circles (DNA contributors), and the actual sample was between 3 and 5 contributors.
For the sake of simplicity, let's assume that there were 3.
The central area where all 3 overlap is where Madeleine's components (alleles) were found. However, because it is where the circles overlap, the content is also shared by other circles / contributors. There is therefore no way of knowing whether the shared alleles were actually from Madeleine herself (an invisible extra circle) or simply the combination of those she shared with the others.