To wonder how they know that aren't siblings?

[WingsofNylon]

I'm watching a documentary I which each person in the couple has been adopted. My first thought was how can they be sure they aren't related?

I've always wondered this of adopted as well as sperm/egg donation children. If you can trace your history back then surely there is a chance that people you sleep with could, at the very least be your half sibling. Maybe, even a tiny chance that could be your parent

Am i bring really dumb and missing an obvious point here?

*can't

It's much more likely that non adopted people in eg small towns are related because so many people are not the genetic children of their fathers.

With sperm/egg donation, if you do it through a clinic there is a register with the HFEA. Each donor can only donate to a maximum number of families in order to try and prevent exactly this situation. People who know they are the product of gamete donation can refer to the HFEA to check any new relationships. Of course there is always a slight risk if someone doesn't know they are the product of donation. But it's a tiny risk.

Morris very good point. That just adds more to the list then.

Pen I wouldn't consider not wanting to fall in love with someone only to find out that were a sibling paranoid. If ever that sort of story hits the news I always think how horrible it must be for everyone involved.

But it does happen albeit rarely. I can remember a couple of weddings being reported in the press as having to be annulled as it turned out the bride and groom were brother and sister

I think the only obvious point you're missing is that I imagine the odds are very very small.

Cold that's the sort of explanation I was hoping someone could provide. Thank you.

I think it would be really unlikely surely and depending on the circumstances and why people were adopted in previous generations then it's highly possible that their half siblings stayed with their birth parents regarding egg and sperm donation if people go down the official channels there are limits as to how often doners can donate aren't there?

I like @MorrisZapp 's answer.

Morriszapp exactly. We live in a smallish town and everybody you speak to seems to be the cousin of somebody else that probably explains a lot

Am I being really dumb and missing an obvious point here?

Yes (speaking as someone who has been researching their family tree for over 15 years), there's no more likelihood of adoptees being related to you than anybody else. The odds are miniscule.

We live in a small-ish rural town, and when we moved here we made friends with a neighbour who told us that she had over 200 relatives locally. Crikey, that's a lot, we thought. And then DH's sister went and married one of them so we became related to her as well!