Really stupid question about boy/girl kittens

[EssexCat]

So we've just arranged to rehome two gorgeous kittens. One boy and one girl (they are apparently siblings but shelter wasn't 100%).
Obviously we will be getting them neutered asap, but in the meantime could the boy impregnate the girl?? They're 3 1/2 months old.

You can neuter/spay from 4 months so I'd get them done as soon as you can. Puberty can happen from 4 months or can be a little later

Exactly. Get them done at four months. That is the current recommendation. If you leave it longer then yes, that is a real possibility

Usually the rescues make you wait until they have neutered them before letting you adopt... could you ask them to do it?

Thank you! Will call the vet tomorrow and book them in, we pick them up Wednesday so hopefully should be soon.

@undertherarrysku they just asked us to get them done as soon as our vet will do it.