Statistics Canada did not allow, on the census questionnaire (though it appears to in other 'variant classifications' used in other data collections), the answer 'intersex' or any other sex other than man or woman. It says it does this because of the small numbers of intersex people and because of other 'difficulties': see further https://egale.ca/wp-content/uploads/2022/10/Brief-on-Statistics-Canada-Sex-and-Gender-Data%E2%80%93Census-2021.pdf, which notes mixed characteristics or intersex assignment at birth could be as much as 1-4%, depending on the population surveyed.
