I know IABU but is it normal to not want the DC to go out/visit certain in laws simply because...

[NickNacks]

I just don't like them?

(the in laws that is not my DC!)

Yes yabvu.

Unless you're going to explain why you don't like them and if those are valid reasons.

My DM hates one of her sisters, but I'm really close to her and like her. Don't carry rifts on unnecessarily.

What Ruby said. It depends on your reasons for disliking them really.

Would you be happy to not see your grandchildren because your childrens spouses dont like you?

Well I know exactly how you feel but I know IABU when I feel that way.
Can the in laws in question take the DCs out wqithout you there so you get a break instead of sitting there biting your tongue? That's what I do when by PILs come to viist, I send them out with the pram and go and get my nails done...

its normal to not like it but its not on to make it known unless there is a legit reason for the dislike and its one that undermines you or endangers dc's

Depends on the reason you don't like them.

If they're horrible people then YANBU

If they just smell of battered cod YABU

It's not a rift and from the outside you'd never know. In more than civil, very friendly in fact but it's an act. I dread seeing them because they irritate the hell out of me!

And the kids probably will go but I'll resent it and feel narky all day.

YABU then, just being irritating is not enough of a reason for the kids not to see them.

Just to re-iterate, I've never stopped them seeing them. It's not grandparents, more distant than that, and they annoy me because they go against what I say in front of dc.

We've always spent Xmas day with them and they spoil the children dispite being asked not to (specific requests)

If they just irritate the hell out of you and haven't actually done anything evil to you, your kids, or Dh then I'd suck it up and visit.
I really dislike my SIL she is becoming her mother more and more each year, but she hasn't really done anything much, just pisses me off with her attitude and snotty face. But I suck it up and visit twice a year with the kids, I refuse to go unless Dh can be there, or my grown sons, this year I will skip the Christmas eve visit, older boys in UK and Dh is working, so Dd and I will do something else. I need back up so I don't get attacked she won't do it in front of Dh or the boys. But I know it's coming, she doesn't know we are moving back to UK and will go ballistic when she finds out.

Without going into more details you do seem very unreasonable. It is hard when people go against your instructions in front of DC but at the same time saying you dislike someone because they spoil children on Christmas Day is a bit

YABU my mum does irritating as an olympic sport. Wouldnt dream of letting it stand between her and her grandchildren though.