Things that you keep from children - bad idea?

[Timetothinkagain]

this is something I debate on and off, and would appreciate your opinions on.
When I was 20/21 (14 years ago) I donated some eggs to enable a woman I knew to have chn. Luckily it worked and she had twins. My immediate family know about this and some were supportive/others not so much. my mum was supportive but also ridiculous and referred to them at points as her 'grandchildren' blah blah. I have never viewed these chn as anything to do with me and have no contact with them or mum. (Out of choice, I didn't want to).
I have since had chn who are now 3 and 1. My husband knows about the donation and thinks we don't need to tell the chn at any point. I'm inclined to agree as its not really relevant to any part of our lives. I do think it's interesting they have a biological link out there somewhere but that's all. However - my mum is cruel at times and also drinks too much. I worry that when my chn are older she'll 'reveal' it to them in such a way that it makes it a big deal and feel I should preempt that somehow. But I also don't want to make a deal out of it or it be something that is discussed by us as a family. It's in the past and should stay there I think.
It's really hard to express on here to be honest, basically if it weren't for the chance of my mum saying something id never bring it up unless the chn ask me directly. What would you all do?

I think I would let your children know, in an age appropriate way, that there are other children out there that are related to them. I'd hope that the mother of the twins is equally honest and lets them know that they were conceived through donated eggs. Things that aren't a big deal tend to become a bigger deal when secrecy is applied. And, since it's not a secret, then it's best to be open.

I agree about the secrecy thing making it seem more of a deal than it really is. I don't want it to be something that becomes an issue for my chn later. The mum has always been open with the twins as far as I know.
Problem being is how and when I guess to let my kids know without it being a fuss. I don't view the donor chn as being related to mine at all. I know biologically they are but then they aren't in any other way. It's bloody tricky. I don't regret donating but hadn't really thought about how my own chn would view it :/

If it were me I'd tell them that, a long time ago, Mummy helped another lady who couldn't have any babies. Just start the narrative there No need for details about eggs and insemination or other grown up stuff that is going to go straight over their head. You did a nice thing for someone, it's part of who you are and, if you repeat the story and add more detail as the years go by, it'll become part of your legend. Hope your husband is proud of you as well, incidentally.

That's a great approach, thanks. There's a small part of me that worries about the indiscretion of kids and my wider family/friends who don't know but their issues with it will be easier to deal with than angry chn later in life In guess.
Hmm proud no, he doesn't like complicated things and views it more as an annoyance in our otherwise relatively straightforward family.

What a great thing to do... I think I would tell them.in an age appropriate way when they start asking about where babies come from. My 7yo is very interested in this recently and knows about sperm and eggs etc so I would just maybe add into a normal discussion on the topic that sometimes women's eggs don't work and they have to be given eggs from someone else that do work. For example, once mummy gave some of my eggs away to help someone have a baby...

I guess the issue would be if they then want to know who they are or if they are likely to come across them?

I was going to post exactly what avocado said. Sort of practical but distant.