Definition of quand même in US English:

Early 19th century; earliest use found in Harriette Wilson (1786–1845), courtesan. From French quand même (adverb) all the same, nevertheless from quand although (1100; 1050 in temporal sense ‘when’; from classical Latin quandō from quam, accusative singular feminine of quī who + -dō (particle) towards, around from the same Indo-European base as to; compare dōnec until) + même same.