We want one child, lots of reasons: time, energy, finances, space.
I know a sibling is not a guarantee firsthand as I have a bad relationship with my own (who does have a little one a similar age).
Apart from siblings child, so one cousin for our DC, there will be no other remotely similar aged relatives for them. DH is an only child with no cousins too.
This in itself is swaying me towards rethinking having a second even if it’s a short term compromise, then they have each other. But can you worry about the future so much when anything could happen?