Longhair is a recessive gene - that means that its "hidden". If the father is a longhair and the mother a shorthair (and her parents are not longhair) all kittens will take after the mother and be shorthair.
If the mother has one parent as a longhair, then she is probably carrying the longhair gene even if she's shorthair (which is dominate over the longhair). Then you would have at least one longhair kitten in the litter. More then likely all the kittens will be shorthair. You might get one longhair kitten in the group.
Just be sure to keep the male from her for a good 4-5 weeks after being neutered - he will still have active sperm and could get her pregnant if they bred.
If the mother has one parent as a longhair, then she is probably carrying the longhair gene even if she's shorthair (which is dominate over the longhair). Then you would have at least one longhair kitten in the litter. More then likely all the kittens will be shorthair. You might get one longhair kitten in the group.
Just be sure to keep the male from her for a good 4-5 weeks after being neutered - he will still have active sperm and could get her pregnant if they bred.