Karen is 199 % correct. The problem with this free to good homes Kittens is taht they end up many times with people who will not neuter or spay them, and that they end up having more Kittens themselves.
If they go to a shelter then sadly some Mature Cats are PTS to make room for them.
I pray that these Sweet Little Faces will find responsible homes and your brother or you will have that poor Momma cat spayed so there are no more littters.