DNA and unexpected results stats?

[coombs]

I know DNA testing for ancestry can throw up some surprises, but will it one day give a % out of 100% a "not parent expected" or "non paternal event" happened out of 100%.

Guy Etchells will give more detail on this, as he often discusses common DNA for ancestor tracing.

I know wartime's saw a boom in extra marital relationships, and it also depended on occupations of the husband, if he was a soldier/sailor, and of course many men strayed. And informal adoptions. I sometime wonder whether I should just concentrate on immediate ancestors or maternal lines?

I think 10% is too high a percentage, more like 2 to 5%. I know it is human behaviour but it can also be a touchy subject and can be hard to accept if there is such an occurrence on a certain line, chucking decades of research out of the window.

[JohnDoe2020]

It can be very touchy indeed. Keep in mind there are many potential ways this can occur that may be unrevealed secrets, besides an affair. Sperm or egg donors, rape and incest happen or just having multiple partners pre marriage. But it happens and it's happened throughout time. DNA doesnt lie...

[Ruskie]

Not too many egg or sperm donors in WW1 or 2. 

[Galium]

But this happened:

https://www.spectator.co.uk/article/a-secret-sperm-donor-service-in-post-first-world-war-london

[brigidmac]

That's incredible....i wonder how many descendants of Derek have tested for DNA and if they know this story

I also want to add that just because a father is not biological doesn't mean that researching his lineage is a waste.

I've included adoptees and adopters and birth parents and named parents in my trees

[coombs]

That's incredible....i wonder how many descendants of Derek have tested for DNA and if they know this story

I also want to add that just because a father is not biological doesn't mean that researching his lineage is a waste.

I've included adoptees and adopters and birth parents and named parents in my trees

This.

Hear hear. Even if not a biological ancestor, their ethics alone will have passed on to the descendants. For example say if a Joe Bloggs was not the biological father of James Bloggs as he was away at sea for a few months around the time Joe was conceived. But Joe bought James up as his, and James learned a lot of his traits and even picked up his accent and phrases, and inherited his surname, then that is enough to consider Joe, and Joe's ancestors family even if not biological ancestors. James would have inherited Joe's ethics and surname, and Joe would have inherited ethics off of his parents.

[JohnDoe2020]

That is a fair assessment. Everyone has two family trees, one based on relationship and one based on genetics. Generally those trees overlap. Your half brother is still your brother. Adopted siblings are still your siblings, sharing the life experiences and lessons as you do. Humans will be human and chance relationships happen for many reasons.

[coombs]

In 1861 the population of England and Wales was 20 million. If 2 to 3% of NPE's took place then, that accounts for about 300'000 people (born to a man other than the mother's husband, or an informal adoption). That sounds about right. It could be a bit higher or lower at this time or other times.

I thought absence of DNA does not mean you can just assume it is an NPE. But DNA that is there that shouldn't be indicates an NPE. Not parent expected. .

[brigidmac]

NPE is a good term for unexpected relationships between married ancestors

But what about when you have a line of single mothers

Any father wouldn't be a surprise !