Have you heard this statistic?

[Peter]

I have heard the 80% figure before from some people who support the DSD nomenclature, but it was in a different context than mentioned above. The version that I read was that 80% of XY karyotype intersex people have conditions that cannot be genetically resolved. That is a very different statement than the statement that 80% of all intersex conditions cannot be genetically resolved. So, you might want to have your friend re-check their sources.

Peter