It does but for babies they have no memory of it..For the 12 year olds its a completely different matter.
One reason more Pagans coinverted to Christianity rather than Jew is because the Jews had the circumcision requirement for adults undergoing conversion, whereas the Christians did not, according to some historians, The whole idea terrified many Pagans.
Circumcision goes back to Abraham, but in Christian doctrine baptism replaced circumcision. Jews are with Abraham. The whole story on how circumcism affected the ultimate numbers of Jews versus Christians can be found in this book, written by a sociologist not a theologan.
http://www.amazon.com/The-Rise-Chris...f+christianity