Im searching for answers. My great grandfather was adopted and I've come to the conclusion that his family was probably Pennsylvania dutch but I need insight please.

The family's last name was Geiger, and the birthplaces I've found were in Lehigh county, Heidelberg township, Berks county, Northampton, and then farther back they come from Baden-Wuttenberg and Switzerland. Do these point to Pennsylvania Dutch or just German immigrants that came here in the 1700's?

if anyone is Pennsylvania dutch can you help me??? (we have no idea why he was put up for adoption)