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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

AIBU to tell my siblings about dad’s secret twin toddlers?

297 replies

ellenred · 17/03/2026 18:08

So I have no idea what to do with this information.

My parents are both in their early 50s, I’ve just turned 30 and I have 2 younger siblings. My mum is a nurse, my dad is a teacher and honestly you would think they are the most well rounded lovely people if you ever met them.

Today I asked my mum if she and my dad want to come on a trip with us. My mum told me they couldn’t afford it and got quite upset. She then revealed to me that my dad has 2 “secret”
children, a boy and a girl who are twins, age 3. She told me that their mum is only 25 and my dad doesn’t see these children ever but sends her £750 a month in maintenance, which is a drain on their finances.
I asked why this is such a big secret and my mum told me that the mum is an ex student of my dad’s, so he has gone out of his way to keep it under wraps. She told me that they had a brief affair.

I feel totally blindsided by this information and to be honest I really want to share it with my siblings who I’m very close to, but my mum has begged me not to tell them.

I don’t even know how to feel or what to think.

Would I be unreasonable to share this with my siblings? They’ve kept this a secret for 3 years and I don’t want to carry the weight of that alone. These children will be about the same age as my eldest!

OP posts:
FannyBawz · 17/03/2026 18:09

Of course you tell them! They’ll never forgive you for keeping that from them

mimi1196 · 17/03/2026 18:09

personally I’d be really clear that they needed to share this information with your younger siblings, or you will. It isn’t fair for it to be withheld from them. Gross from your dad also..

LadyVioletBridgerton · 17/03/2026 18:11

It’s not your secret to tell. Be there for your mum, she’s upset enough as it is and you telling your siblings will hurt her even more. Frankly, I can’t believe she’s stayed with him. This would have been the end for me. Is this going to ruin their retirement? I hope she’s not going to work longer to help find this £750pcm. It’s your dad’s responsibility alone.

TomatoSandwiches · 17/03/2026 18:11

God your dad is fucking disgusting.

Yes tell your siblings, maybe you can all help your mother leave her vile husband.

DramaQueenlady · 17/03/2026 18:12

They probably need to know. But its not your place. Support your poor mum in this. Explain everything how you feel and let your dad explain.

Gonnagetgoingreturnsagain · 17/03/2026 18:12

Tell your siblings.

Blondeshavemorefun · 17/03/2026 18:13

Yes you have to tell them

£750 is a lot

it’s usually 16% of gross wage for 2 kids so unless your dad had a very well paid job seems high

how did they come to that amount

your poor mum as well. To know her dh in unfaithful but guess she has chosen to forgive him

anddeepbreathandsigh · 17/03/2026 18:13

Your poor mother. She sounds like she’s having a breakdown keeping all that to herself. Your dad has put her and now you in a terrible position. I’d tell him to take responsibility and tell your siblings and take more care of your poor mother and by default you. What a bastard really.

deismevav · 17/03/2026 18:15

Definitely tell them. Your poor mum. Why is she protecting him? The truth always comes out in the end.

Arlanymor · 17/03/2026 18:16

Why is your dad not being responsible and stepping up to tell your siblings? Your poor mum.

Brewtiful · 17/03/2026 18:18

Well given they currently think your father is a decent man and your mum sounds like she's on the verge of a breakdown not to mention these siblings would be entitled to inherit when he dies then yes you absolutely need to tell them.

Hollowvoice · 17/03/2026 18:21

Oh your poor mum.

BudgetBuster · 17/03/2026 18:23

I would 100% tell your Dad that either he tells your siblings by X day... or you will tell them. Its not up to your poor Mother to carry his lies.

Also... keep checking on your mother. Is she OK? When did she find out? Does she really want to stay with your father or is she staying because she feels she has to?

Drippingfeed · 17/03/2026 18:27

Brewtiful · 17/03/2026 18:18

Well given they currently think your father is a decent man and your mum sounds like she's on the verge of a breakdown not to mention these siblings would be entitled to inherit when he dies then yes you absolutely need to tell them.

They are not entitled to anything unless he dies intestate or they're in the will.

BlueMum16 · 17/03/2026 18:28

Your poor mum but this is not your secret to tell.

You need to sit with your parents and let them know you you and that they need to tell your siblings.

Support your mum.

Your dad needs to pay child support but 750 sounds really high. Is he paying over the odds? This needs addressing if not only to lighten your mum's load.

You need to help them stop burying their heads.

Your mum may need support to leave him or they made need support to stay together.

Your mum should be your priority.

BuckChuckets · 17/03/2026 18:30

TomatoSandwiches · 17/03/2026 18:11

God your dad is fucking disgusting.

Yes tell your siblings, maybe you can all help your mother leave her vile husband.

This 👏🏼

ellenred · 17/03/2026 18:32

BlueMum16 · 17/03/2026 18:28

Your poor mum but this is not your secret to tell.

You need to sit with your parents and let them know you you and that they need to tell your siblings.

Support your mum.

Your dad needs to pay child support but 750 sounds really high. Is he paying over the odds? This needs addressing if not only to lighten your mum's load.

You need to help them stop burying their heads.

Your mum may need support to leave him or they made need support to stay together.

Your mum should be your priority.

Apparently the official amount is around £600. He pays extra as he quite literally never sees them, but this is by choice.

OP posts:
WelshRabBite · 17/03/2026 18:33

Yes tell your siblings.

Shame must change sides.

This is not your mum’s burden to carry, she needs the support of those that love her and your Dad needs to be told what a disgusting old man he is, and a potential groomer; having sex with one of his students 🤢

Chatsbots · 17/03/2026 18:34

Well, that's as dodgy af.

Nope, it's time some sunlight was shone on this mess.

In the long run, it will be better for your mum, the OW & the little kids.

Brewtiful · 17/03/2026 18:34

Drippingfeed · 17/03/2026 18:27

They are not entitled to anything unless he dies intestate or they're in the will.

Illegitimate children can contest wills. Although given he's paying over the odds in maintenance then I would suspect he will also leave some to them in the will. Either way the ops siblings will find out.

purpleme12 · 17/03/2026 18:35

I would speak to your mum or dad (or both together) and tell them they need to tell your siblings or you'll have to

I don't think it's something you should be keeping to yourself no

gerispringer · 17/03/2026 18:36

I would tell them. If you're close to your siblings you couldn't not share this with them. They need to know.

Deerinflashlights · 17/03/2026 18:37

Honestly I think this is deeper. The ex student part of this has the potential to really destroy your Dad depending when the relationship started and I suspect that is part of the reason the child support is so high. Your father needs to come clean to your siblings. His behaviour is awful.

ThejoyofNC · 17/03/2026 18:39

I pity your mum. She obviously feels like for whatever reason, she can't leave that vile man. I wouldn't keep his dirty secret for him. Give them a week to tell your siblings or you will.

BlueMum16 · 17/03/2026 18:41

ellenred · 17/03/2026 18:32

Apparently the official amount is around £600. He pays extra as he quite literally never sees them, but this is by choice.

Personally I would be encouraging your mum to have a conversation with him about why he is choosing to force her into hardship by paying over the odds.

I do hope they have robust wills in place. Both of them. Your mum's assets could go to your dad and then his secret kids and you and your full siblings could miss out.