Resin. Polyurethane resin. It's plastic, folks! It's not clay or glass or solidified tree sap. Your dolls are made out of plastic. It's very nice plastic, but it's still plastic. If you want to look down on those plastic dolls, maybe you should invest in porcelain.
...ahem. Sorry. That's not actually directed at anyone here. I just happened to come across DoA's thread on Hujoos... you know, the ones that are virtually indistinguishable in their polyurethane and ABS incarnations, but off topic if they're "plastic" instead of "resin."