To let my step daughter call me "mum" ?

OP, I think you are being too hard on yourself. So many posters on here have projected and speculated that his upbringing is the cause of his issues. If anything, it seems to me that he has had a very loving upbringing with many people in his life who love and support him. Perhaps you have been too indulgent, but there are many external factors that affect a young person's acquisition of attitudes and values, especially these days with easy access to all sorts on social media and the internet.

Hopefully, your son can get the help he needs to resolve some of these issues, and your whole family can move forward.

What an apposite user name for that post! You’re absolutely right, kicking out would be the worst possible thing.

Sounds like his going to pushing any button he can to try and get you to react. If you kick him out that’s your choice but you will just add fuel to the fire with how he feels about her invading his family.

I honestly don’t think you should blame yourself @Lospecesenelrio. We all do the best we can and you were so young when he was born. You’ve raised him thoughtfully and carefully, this isn’t your fault.

He seems to be pathologically jealous and resentful of his sister for some reason and he clearly needs help to unravel and process the cause of that. A therapist should be able to help him but the issue is that he’s an adult and has to accept that he needs that help. It’s a horrible situation all round.

Sounds like he is ramping things up, as he is getting more desperate to stop it. He is being totally and utterly irrational now, and you must be at your wits' end.

I don't think anyone here can help you. As you and your ex have agreed, it's time for professional help - if your son will accept it. He's just utterly filled with resentment, isn't he?

He does need reminding though that he doesn't get to call the shots. It must be very hard to tell him you love him when he is coming out with such crap. You are so much more of a patient woman than I am. I would have lost my shit, I'm afraid. Sounds like he's been too used to getting his own way.

Your son is being childish and ridicilous. Tell him so. Tell him that you can make decisions for yourself and neither he, nor anyone else has the right to tell you what to do. That he has no right to control anyone and that he needs to give his head a shake.

He’s not really William, it’s for the purpose of the thread.

OP I’m so sorry, he’s really showing his true colours with this situation. Either way, his behaviour is extremely manipulative and professional help sounds like the right idea.

It is more likely that he is just saying whatever he can to get you to do what he wants (I.e. not let her call you mum) than he genuinely is sexually attracted to her, but that is still unacceptable and highly manipulative. If your instinct is saying he is dangerous, listen to it. It may just be a warning sign that he will become worse if this behaviour is left unchallenged further.

I would still be mindful of him with all of your daughters for now, as of course better safe than sorry, but it sounds like he has been harbouring extreme jealousy toward your SD. I would be explicitly clear that it would be illegal for him to pursue a relationship with your SD as they have grown up in the same home together whilst both children. (I believe this is correct, I think it’s legal to marry your step sibling if you met as adults/didn’t grow up together, but not if you didn’t, but could be wrong.) In either regard I would assume you’d say to him his twin sisters could be supermodels and it would be incest regardless of how any of his sisters look!

I would almost be grateful that he is making these statements so openly now, as it means you know he needs help and support and it’s serious. Better that than him festering on it, pretending he doesn’t care and then harming your SD in some way.

It sounds to me as if you are constantly trying to reassure him, as if this all comes from a place of distress rather than malice. I think he needs telling to shut the fuck up, and to put on his big boy pants and deal with it. She's his sister, he won't be "falling in love " with her, and anyeay, what makes him think that she would see him as anything other than her nasty brother? He needs to give his head a wobble, and perhaps you need to stop pandering to his moods.

@Lospecesenelrio OP it's awful what you are going through... I think you mistakenly named your DH. you can report your own post to get it deleted or see if you can edit it...

should NOT offend

I've read all your posts, OP. You sound lovely, warm and caring and I can well understand why your SD wants to call you mum. Your son...sounds difficult. Realistically, anyone else he tries to moan to about this will tell him he's being a ridiculous little drama queen. I wonder if perhaps you might do the same thing.

I think it’s lovely that throughout this thread you refer to her as your daughter, only once referring to her as your step daughter… the absence of mum must be so hard for her… Your son is incredibly selfish and immature.
I would maybe write him a letter that he can read and process in his own time, explaining that while she is not your bio daughter, she has been in both your lives since she was a toddler… also that she shares half her DNA with the Twins, as does he!…. Which gives them a special link as they share biological sisters! I’d also write that while he’s very lucky to have a very caring dad who sees him and supports him, she has a mother who for various reasons hasn’t seen her for 4 years…. And ask him to consider how that rejection must feel to a girl who is heading towards puberty/seniors etc…. If calling you mum makes her feel secure/wanted/loved then surely he doesn’t resent that (put this in letter)..
Tell him her wanting to call you mum is a privilege to you, and you wish he’d see her as his sister as much as the twins are… she wants and needs to be part of the family and being the only one without having a mum must be heart breaking.
Being a parent is about so much more than just biology, and I’d tell him that, and tell him that you’ve raised her and bathed her and dressed her etc, and that is why her calling you mum should offend him! And again being called mum or dad is an honour and obviously if her own mum was around you would maybe discourage it because she had a mum and you wouldn’t want to upset her, but since she doesn’t have an active role in your daughters life then you don’t mind and neither should he!

Don’t say this obviously but I find your son very manipulative, he emotionally blackmails by giving you the silent treatment until you give in… or threatens to never talk to you again….. let him give you the silent treatment.. let him stay at his dads or girlfriends and sulk….. he will need you or need to come home so will have to back down…or maybe the space will make him consider if this is really all that bad… if being called mum is a huge deal, and he sees it as some huge thing that you don’t mind him called his step mum ‘mum’… then surely he see parents as some massive thing in his life which is lovely…. Except he doesn’t because if that were the case he wouldn’t even consider ‘never’ talking to you again! … next time he makes such a threat tell him that such a threat is contradictory of how important he ‘says’ the title mum / son is… and that this time his threats and tantrums won’t work, because he’s a grown ass man who should be able to see that her calling you mum doesn’t change anything because you already love and treat her like a daughter anyway!! And that one day if he meets someone with a child already you’d hope he’d treat and love that child like his own and would hope that he’d be happy for them to call you nan/grandma etc same as his bio children would!!
Then just leave it… let him think it all through, let him realise that this is how it is now and no amount of sulking will make you act cruelly to your eldest daughter… she’s probably been trying to pluck up the courage to ask you for a long time, feeling different and not fully in the family because she doesn’t call you mum…. I think you’re a rare treasure @Lospecesenelrio and more step parents should be like you. Tell your son in no uncertain terms that he’s always going to be your special boy…but you have 3 daughters and whether she calls you Sue or mum won’t change the fact she’s your daughter in your heart!The same as he’ll always be your first born, your Son and you’ll always love him !!

like I say, let him sulk, let him strop… don’t back down .. he’s an adult and needs to grow up and also needs to recognise that she IS your daughter, and calling you anything but mum like her 3 siblings singles her out and makes her feel that little bit ‘OUT’ of the unit!

and let’s face it, she will always be aware of the fact you’re not her real mum, the same as he will always feel you’re not her ‘real’ mum…. BUT if calling you mum makes her ‘fit’and helps her through the teenage years then that 3 letter word is worth more than anything!
That little girl will always remember the first time she called you mum and will treasure your acceptance! Imagine the rejection of you saying ‘you can’t call me mum because Fred doesn’t like it’…

I hope your son grows up and turns into as nice a person as you and his bio father sound! Your family dynamics of you all getting on and supporting each other sounds amazing!

sounds a bit mean

ask him to try and think like your SD, she’s trying to fit in a feel safe

he sounds jealous and needs to grow up

So you’ve known your step daughter since she was 10 months and her own mother is pretty much absent from her life? You are her mother. Your son is being ridiculous and seems to lack empathy or compassion. I wouldn’t be taking him out for a chat and indulging in any of his shit, he’s 19 not 12 and he sounds incredibly selfish.

Does your step-daughter know this is how your son feels about her calling you “mum”?

I agree with the majority here that your DSD should be able to call you mum and your DS doesn’t have a veto on this bid needs support to unpick why he feels so strongly about this.

My concern would be in the interim that any reaction from your DS doesn’t create lasting damage, which I would be worried about if DSD knows about your DS’s feelings.

Well you have done the right thing especially having his dad supporting to. Now I think you just have to stick to what you feel is right. There is a bit of a catalyst time here for your son who has to learn that he cannot always have things his way and that he has to accept that others may do things differently to what he wants. And that bad behaviour is not appropriate to manipulate people to get his own way!

If he complains repeat that you love him and tell him that it is his prerogative to disagree with you but it is your prerogative to do what you think is right...and that your actions/decision do not impact in any way on how you feel about him as your birth son/you as his natural mother - he does seem to find this aspect very important so worth referring to.

You are a thoughtful and emotionally intelligent mother who sees the good and the less nice aspects of your sons personality which is important in helping him to grow into a mature and resilient adult over time

I think your son is completely unreasonable but I think you need to show him some empathy and have a big chat or maybe even a joint counselling session about why he's so upset.

If he refuses to engage, I'd keep doing what you've been doing and sod him quite frankly. It's lovely that you're there for your step-daughter.

Tell your son you may not be her mother but you are her mum. Whilst you did not give birth to her you are raising her, just like you raised him and the twins. She is your daughter legally through marriage as well as in your heart. It does not change the relationship with your son the same as having more children naturally did not change this. Adopting her would not make any difference to how you feel but I doubt he would suddenly change because you are legally her mother. My son has called my partner dad since he was 2 as dp raised him when his father has been mainly absent. I always refer to dp as his dad and the bio waster as his father. The term in the dictionary basically refers to the sperms donor rather well where as dad clearly states the man who raised you. I should imagine mother will mention the one that carried you and mum being the person who raised you. If so I would show your son and say he is lucky that to him you are both of these where as to her you are a mum.

Ooh I hadn’t seen these.

Great explanation. (From @Devonshiregal particularly)

I’m not keen how some parents talk negatively about their (barely) adult children, self-reflection is always key in the parent too, it’s not always ‘parent knows best’.

Perfect post

Hes not a bellend. He's a young immature man who is struggling and needs help to work out all the confusing feelings he has