You've read the threads. You've watched the documentaries.
One line keeps coming back: "DNA testing is so common you'd likely be identified."
So is "anonymous" a promise or a hope?
Here are five plain truths, so you can decide with your eyes open.
1. "Anonymous" means the clinic keeps your name
The clinic keeps your name. Your second cousin's spit-in-a-tube kit doesn't.
That gap is the whole story.
"Anonymous" means the clinic won't release your name. It doesn't mean nobody can work it out.
The viral "quick payout" videos skip this part.
One donor who gave six times wrote that a donor-conceived child "appeared on 23andMe and matched with my mother."
She had never tested herself.
Her anonymity slipped away through a relative's kit.
Knowing that before you sign is the difference between a surprise and a plan.
2. You don't have to test to be found
You can skip every DNA kit on the market and still show up in someone's results.
Donors describe a mother, a sister, a brother or a second cousin becoming the thread.
One donor asked the company to make sure she couldn't be traced.
Her donor-conceived daughter still found her, through her brother's test.
Turning off DNA matching on your own account doesn't settle it either.
Commenters say relatives' matches and family trees can still point straight to you.
So your privacy is shared with every relative who might get curious about their ancestry.
That sounds heavy, but it gives you something to work with.
The useful question is whether you'd be ready if a relative tests.
You can answer that one today.
3. Nobody can hand you an honest number, so read the contract
You asked how often it really happens, and I don't have a number for you.
The research I'm working from doesn't offer one, and anyone quoting a rate is guessing.
What you can read is your contract.
Many donors signed before consumer DNA testing existed.
Some now feel misled about something the industry never could have promised.
Today, donors are told to avoid the word "anonymous."
Photos, social media and DNA tests mean "there is no 100% guarantee."
One donor was asked in a forum whether she was comfortable being contacted by a child.
She realized nobody at the clinic had ever asked her that.
So bring your own questions.
Ask what the contract promises if a match reaches the clinic.
Ask whether the clinic will pass a message along.
Ask what support exists after your cycle is over.
Ask whether you'll be told if a birth happens.
Ask them to explain non-identified, semi-anonymous and identifiable donation in writing.
A clinic that answers plainly is giving you a good sign.
4. Open, semi-open and closed give you different things
Closed sounds safest, and it also comes with silence.
A donor from 2000 doesn't know if her eggs produced anyone.
Another said it plainly: "Anonymous so they don't tell you if the intended parents were able to conceive."
Donors in closed arrangements got letters or cards, but no identifying information.
Some wanted photos and updates and never received them.
Donors in known arrangements describe getting updates and photos as more fulfilling.
There's a middle path too.
Many donors say they'd share medical history or have a conversation, but "don't want to be involved in upbringing."
Commenters keep urging the same thing: go slowly, and ask what the family expects.
If you'd like to be found someday, say so.
One donor told the intended parents she hoped to be contacted and pointed them to the Donor Sibling Registry.
You get to choose your own terms before anyone else chooses them for you.
5. You can decide your terms now and live well with them
You wonder how you can sign at 26 and live with it for 40 years.
You can't be sure you'll never be found.
You can know exactly what you'll say if you are.
You're not paranoid, and you're not naive.
Reading this much before signing is what careful looks like.
Take the viral donor who wrote "I am not your mother."
She called the contact "a major breach of privacy."
The young woman's message was tentative.
She asked only for a DNA test and to get to know her.
The exchange set off a viral firestorm of blame and defense.
A reply written in a panic lands hard.
A reply written ahead of time can be kind and firm.
Donors ask, "what kind of relationship, if any, would be suitable?"
No clinic hands them a script.
So write your own.
Decide what you'd share, and what you wouldn't.
If you have kids or plan to, some donors tell them about possible half-siblings before a match does it for them.
One donor looked back and said, "At 22, you don't always get the hugeness of a person's entire life."
You're putting the hugeness on the table first.
Another donor wrote, "I did this because I wanted a mother to exist that wouldn't have been otherwise."
She ended up meeting that mother and the child.
Write your terms down.
Then take your questions to the first agency on your list.