Status of Jews before Matan Torah and Why Jews Stink

I will be giving a shiur next Shabbat, and I want to speak about the machlokes between Ramban and 'the French Rabbis' (quoted by Ramban) about the status of Bnei Yisrael before Matan Torah. Ramban is commenting on Toras Cohanim (cited by Rashi) at the end of the Parsha which states that the 'blasphemer,' who was the son of a Jewish woman and an Egyptian man, converted.
The French Rabbis (i.e. baalei Tosefot) claim that before Matan Torah Jewish identity went through the father, and only after the Torah was given did the Jewish people follow matrilineal descent. For this reason the 'blasphemer' had to convert.
In other words the descendants of Avraham remained B'nei Noach, with extra 'stringencies' of being part of Avraham's covenant. But they did not take on the 'leniencies' of being Jewish until after the Torah was given.
Ramban argues strongly on this, and claims that from the time of Avraham the Jewish people had unique laws and were no longer considered to be B'nei Noach at all. Therefore Ramban says that there was no need for the 'blasphemer' to convert. So the midrash must be referring to the 'conversion' at Mount Sinai of all the Jewish people.
Parshat Derachim is a book written by the author of Mishne L'Melech, which builds almost entirely on this idea of whether the Jews were considered Jewish before Matan Torah or not.
So that is the outline of my shiur for next Shabbos (if you are a woman and wil be in Har Nof next Shabbos afternoon you are welcome to come. The shiur will be in 16 Brand at 4:45 - I think).
Over Shabbos I was rereading Stephen Jay Gould's 'The Mismeasure of Man' and he refers to Sir Thomas Browne's 'Pseudodoxia Epidemica' which is a
One of the chapters there debunks the myth that Jews stink. After demonstrating that Jews in general to not smell, and explaining that their eating habits and hygiene habits are unlikely to cause them to smell, he adds another point, which is that Jews are so assimilated and intermarried, that it is impossible to make any biological claim about Jews. There are many Christians who are biologically Jewish and vice versa. Therefore any claim about Jews, based on their ethnicity, is necessarily false.
This is a point that is worthwhile for us to always remember, especially with debates about 'who is a Jew'. The attributes of a Jewish person are not determined biologically, but through halacha, and through our behaviour. The 'blasphemer' became infamous not because of his parentage, but because of how he acted. Yichus is all fine and dandy, but the key thing is how we act.
Of course if it were true that Jews do smell, it would solve the conversion crisis in a minute. The Beis Din could just train sniffer dogs, and would know whether or not a convert is sincere, and whether or not the Beis Din that converted them was kosher.