Confused about dna test

[scientificexplanations]

If someone's paternity was being dna tested, so a son was seeing if his dad was actually his dad why would the dna company then want to test the son's mother ? Anyone know ? As to me this doesn't make sense because obviously the mother is no relation to the dad so not sure why their dna would be tested too??

I don’t know but off the top of my head it could be so they know the dad is not the dad because eg the mother cheated rather than the dad is not the dad because of a switched at birth scenario? If it was a huge court case with an estate and heirlooms and stuff at the heart of it, it could just be that it needs to be a solid ‘this is the situation’ rather than ‘this is one scenario’?

It's my brother, he never knew his dad but my mom always said she was adament who his dad was. Due to a situation now my brother is having to prove who he is through the courts, they did his dna test but have now asked for my moms too for an accurate result or something.
Could it be this man isn't my brothers dad afterall??

I’m sorry your family is going through this.

As I say I don’t know but if I was in this position I would assume it was just for the sake of absolute clarity. And again I’m not sure but if it was me I would also assume that the man I was being tested against wasn’t my father. However, you say he is having to prove in court who he is so it could be that man is his father but they want to be definite about his parentage entirely rather than just the paternity side.

Thank you. It's to do with an inheritance, my brother was named in the will but nobody knew about him ! It's like eastenders honestly.
My mom is so worried about it all, she says she can't remember but is adamant that's his dad and always has been

I think they want to test your mother is his mother as well just for the sake of absolute clarity. Does your brother have a lawyer working on his behalf that he can ask for advice about it? I would ask Mumsnet to move this to the legal section and also post on reddits legaladviceuk subreddit to hopefully reach the attention of people who have some knowledge about these types of cases.

I really hope everything works out well for your family in the end.

Google says:

They are using his paternal aunties dna aswell.

Why would they need to get a more accurate result of the fathers dna though ? Surely it's just there if he is his dad?
Yes I could've googled but would be good to hear from people with experience in this

Thank you. And no I don't think he does

As mentioned, the more DNA they can attribute to a blood line the better. So using several relatives can help

Maybe to check % of sharwd dna? The df could be an uncle /cousin /second cousin. A level of 47.5 is shared between a df and a ds....
*I was this week old when I learned that....

So why would they not just do that in the first place? It is just prolonging it all

I think it is likely cost, so they start with just the minimum but if they need more request it at a later date. I haven’t dealt with DNA on a commercial side as such, the knowledge I have of DNA is through my uni days in forensics. I may be completely wrong but I would think they will do the least invasive options first as there’s a lot of sensitivity around extracting and storing DNA profiles