Yes but if you refuse they go to the judge and say that you are hiding something and get an order to remove your children from your home based only on the fact that you would not let them in your home without a warrant. (I've seen it done) Your damned if you do and damned if you don't.
I forgot to mention: MAKE SURE YOU IMMEDIATELY HIRE A LAWYER who specializes in CPS type cases. Don't wait for them to come back with a warrant.
Once they know there's an attorney involved, they watch their behinds to make sure they don't screw up. In fact, they will often drop a case when an attorney is involved in the early stages. There are too many indigent folks out there who cannot aford to hire an attorney that CPS can turn their sights on. If you make it difficult for them to violate your rights, it's easier to concentrate on some poor saps who don't know their rights. However, if you don't have an attorney, they can run roughshod over you, disregarding the Constitution, for the children of course.