In one of the 1st episodes, when Ted mention Robin, the kids shout "aunt Robin???". So clearly, it's not their mum...

I agree with Plasmide; he wouldn't have said 'And that is how I met your aunt Robin'

Robin's what?
(Sorry I couldnt help my self)

sorry robin sister

why are you screaming?
and if this contains any spoilers and you're gonna go
"well i read in XYZ" i swear ill freak!

if this is a spoiler then mark it as such please if it isnt..well i have no idea if the mom is robins sister

No, I think when he says Aunt Robin, she is just an aunt in the way that best friends become aunt. I doubt she will be blood related, if the writers had that planned I think they would have made her sister much older.

Plus, it's also Uncle Marshall, Uncle Barney and Aunt Lily.

No, he calls her aunt Robin

oh thats the angle..the "aunt robin " oh-wait-i-found-something-angle

:) all good then carry on..mind editing the pick via the little pen symbol to add sister to the question? and while your editing you could erm amybe just write regularly!? NOT ALL IN SCREAMING CAPS?

yay :))))

yea remember aunt robin? and those pictures of son and daughter and aunt robin at the zoo and stuff? it can't be her ;)