I saw a comment earlier about use of the words sex and gender and how gender used to be a reasonable synonym and sex just results in teenage dissolving in mirth. I couldn't find the comment again. But the idea was we should find a word to replace sex.
Sex is the correct word because it links to sexual intercourse which is part of sexual reproduction. We need this word precisely because of the connertations behind the sniggering. Sex (male/female) is primarily about reproduction - it is our reproductive roles that govern our bodies and how we are treated. Any other words obscures this. It is also a word with consistent meanings right across phyla.