Sex & Sexuality

So I'm currently taking a sex and sexuality in literature class and we are reading a book called Herculine Barbin and basically the main character is a hermaphordite who struggles to understand her sexuality as she feels that she wasn't born with the right  sex (no one ever told her she was born with both). So my professor today was like so what is sex? And obviously people were like oh it's based on science xx is female and xy is male. And then he said yea but what about xxy or xyy or xxx or xo and that's when everyone got quiet. He went on to say that sex isn't a binary thing that it's not 1 or 0 but rather a spectrum and that to say that it is binary is to exclude a vast number of people as it's not as rare as everyone thinks. So what are your thoughts on this?