Cousin dating our cousins updating builder cabinets
It doesn't sound like you get on well/have a close relationship with your brother anyway (and I have sympathy- my brother is a complete pain), so I doubt you want to have a close relationship with them. One of them is my first cousin, and the other is first cousin to him but not to me, iyswim. They are immensely happy together, the most compatible couple I've ever come across in sickness and in health etc. Your brother and your cousin could be making the most successful relationship in your whole family.
It would probably be a good idea - if they decide to have children together, because 4 kids isn't anything like enough after all - for them to have their genes checked, if it's possible.
It's not something I would choose to do, but it's hardly unheard of. If you can't be pleasant and keep your opinions to yourself when in their company that maintain a dignified silence and keep away as much as possible.
Not sure what you would hope to achieve by telling them exactly what you think about their relationship.
We live in a small town and it's only a matter of time before their school mates clock on.
We were very close as children and went on holidays etc together.
This is as true with DNA evidence as it is with any other type of genealogical evidence.
This is a very high burden, but that is required to establish that the case isn’t actually the MUCH more common occurrence of misattributed parentage.
After all, Occam’s Razor suggests that misattributed parentage (no matter how much the parties may protest) is significantly more likely.
For example, both DNA test results and traditional genealogical records can reveal misattributed parentage, adoption, health information, previously unknown family members, and errors in well-researched family trees, among other unexpected outcomes.
This is especially true when testing two people who are second cousins or closer, as there has NEVER been a single demonstrated case of second cousins or closer who fail to share DNA.