gentiles - Was Eisav Jewish?

Was Eisav Jewish? Eisav was born to the same father and mother as Yaakov. It may be possible to say that Yaakov was not Jewish either as it was before Matan Torah, however if Yaakov was Jewish, then was Eisav also?

Answer

The Gemara (Kiddushin 18a, top) calls Eisav ישראל מומר - an apostate Jew.