Would it be odd for twin boys to share a middle name?

Yes this. Just look up all the variations of John and pick two. Don't give either of them John.

I was going to say something similar.

John and James for example.

Nope - every single male in my family has the same middle name going back about 4 generations. No idea why that started but impossible to stop now!

I have 3 girls and they all share the same middle name mainly as it’s my middle name. We joke they’ll have to carry it on eventually. My parents have no idea where my middle name came from although my dad jokes it was his favourite page 3 girl in the 80’s. I figured one day the girls may ditch their surname but there’s no escaping their official link to me!

Dh and his brother have the same middle name, as do the other men/boys in the family.

So no, not weird.

I agree, I don't think it's unusual for siblings to share a middle name (especially if it's a mother's maiden name - which is, or at least used to be, quite common in Scotland I think).

Given twins will probably share a DOB and surname, I think if they are also going to share a middle name then the first names should have a different first initial.

I don't see an issue at all so long as their first names are sufficiently distinct (John is lovely BTW). Hardly anyone in their lives will ever know their middle names and presumably if you have more sons they will have John too so it is just a nice family thing that ties them all together. You've got enough of a challenge coming up with two first names at the same time!

All my 5 children share a middle name. Its my last name but is also a gender neutral common first name. I didn't realise it was weird until I had already given it to my first three and I couldn't then not give it to the the younger two without them being the odd ones out!

Honestly I can't really say that I care if anyone finds it odd. My kids don't care and it's not like you routinely go around asking sibling sets for their middle names.

I’d give them each two middle names-

first name second name John Surname

Both my boys have my maiden name as their middle name so I don't see it as being an issue!

At my primary school there was a family of 3 girls who all had the same middle name. It also rhymed with their unusual surname and alliterated with their first names. Made them sound like a matching set of dolls. eg Millie May Doopeyday, Martha May Doopyday and Margaret May Doopeyday.

I also taught twins who were called something similar to Ellie-May and Ella-May (hyphenated rather than middle names) and again I just thought it made them seem like a matching set not their own person.

so I wouldn’t do it!

What about different versions of the name, eg John in Welsh is Siôn, Ioan or Ieuan. In Irish it would be Sean.

Twin here, my twin DSis and l have same first and middle names but in reverse. Think Kathryn Ann, Ann Kathryn, obviously nothing like our real names.
Nightmare tbh as my dsis is terrible with money, lots of people chasing and l get debt collectors chasing me and then when they find out same D.O.B etc as well as first two names, they won't accept it. Just think I'm trying get away with it. DSis couldn't care a jot, bless her.

All five of a friend's grandchildren have the same family middle name.

Can you give their grandads first names aa middle names?

I'd give them three names with one in common.

Identical twins in my family have the same middle name (which is a family surname from mother's side). Never been an issue. Middle names are never asked for so who even knows a person's middle name, and although they are seen very much as 'the twins' now, that's because they are teenagers and at school, clubs together. Once they are adults, which they will be for the vast majority of their lives, most people probably won't know them as one of a pair. They have first names with different initials so no issues there.

I share a middle name with my sister (not twins), and my mother and my grandmother come to think of it. Probably a few other relatives going further back!

It’s Anne, so hardly revolutionary but it’s seemingly a family name.

Have just realised this second that I probably should have given it to DD, but she’s 6 now so it’s probably a bit late!!

I have rwins and as long as you treat them as individuals I would think ok. However make sure they have different initials as when you have the same dob and initials it could get confusing.

I think either do it for both or neither but not just one of them. If the name actually is John, I definitely think it's fine, it's almost like a second surname.

To be honest middle names are a waste of time at best and an embarrassment at worst so I don’t think it really matters if they have the same middle name.
How about just not giving them a middle name, makes life much simpler.

I think that’s lovely if it’s a family name.