To ask MIL to stop posting photos of DS on social media?

If you want to go nuclear you could flag the photos up to FB and ask to have them taken down.

Totally reasonable, I posted one picture of myself with my very tiny GC after my daughter had done a birth announcement post. Since then maybe two posts but taken so you can’t see his face or identify him. You are allowed to set the rules for your children and the wider family should respect them.

Totally reasonable. I never post photos of any kids ever let alone someone else's child, that's widely understood now IME.

YANBU.

You just need to be strict about it. I had a similar issue.

Older people often seem a bit naive about social media.

It’s just excitement - they want to share their lovely grandchild with their friends, but they aren’t thinking beyond the immediate. I don’t think my mother regarded it as any different to a friend coming round and seeing a framed photo on the wall.

Once their image is out there, it is difficult to control. You also don’t know who her friends are on Facebook - it’s different to sharing with your own group.

I found it particularly grating having all these people I had never heard of commenting on me and my kids. So very weird - I don’t want there to be a chain of comments somewhere on the internet about me or my kid.

A good way to describe it which might be easier for her to understand, is in saying that you don’t know how your child is going to feel about their photos being on the internet when they are older, so you want them to be able to make that decision themselves.

FYI I do share some (limited!) photos of my child - but only if I have control over what it is, who it’s shared with etc. I would probably concede on my mother sharing the odd picture if pre-approved by me. So I’m not extreme on privacy, just trying to be sensible!

I think you are being perfectly reasonable about this and have explained your views politely. Your MIL will just have to accept your views - you are the parents. If she wants to sulk that's up to her.
I don't understand why some grandparents are so obsessed about posting photos of their grandchildren on social media ( I'm a grandmother btw!)

We don't let anyone post photos of our kids on their social media, ever. We always have to ask people to take posts down so I don't think you're being unreasonable.

Your baby, your decisions.
However, you will have to find a way of stopping her taking pictures of him, which will be a challenge.
But stick to your guns!

Yes she sounds upset so maybe sit down and have a chat? You can talk about your reasons for your feelings (which are very valid) and that although you are really pleased that she is so proud of her grandchild, perhaps she could show the pictures on her phone when meeting her friends in person?

It is your choice as the parent but just to warn you it is a minefield and you might want the option to change your mind later. Unfortunately social media is now a part of everyday life.

Nursery, sports clubs, school and everyone else (friends/parties) will be requesting permission to post your child and it will be quite obvious to them if they are not included (with everyone else).

My compromuse is that my children age 8/10 now control the narrative. I also ask that they are not named or tagged and although they are on my feed, I have strong privacy settings.

And don't send her any more photos

Absolutely fine. The Internet can be a very dark place at times and it's perfectly reasonable to reduce the chances of your child being caught up in that. It's possible your mum isn't up to date with eg AI & Deepfakes but there's a petty disturbing article in today's guardian if you wanted to spell it out to her