If the house is new enough to track down who did the plumbing I would start there. Your drains should be fine if no problems have arisen thus far. The supply lines are different. There have been problems with Poly-B pipe in the past. It is grey, and uses a crimp style fitting. Poly B has been replaced with Pex pipe that (allegedly) will not suffer the same problems as poly B. Copper is your best bet for peace of mind. If it is copper, and you cannot speak to the plumber, I would look under some sinks to get an idea of the quality of work on soldering and assembly.