Since some people have been asking about this recently, I thought of The Bump when I saw this article today:
https://www.huffingtonpost.com/2014/02/13/facebook-gender_n_4782477.htmlIt gives a little more insight into the "between the legs" vs. "between the ears" idea. There is also this Maclean's article from not too long ago, which I forgot to post at the time:
https://www2.macleans.ca/2014/01/13/what-happens-when-your-son-tells-you-hes-really-a-girl/In a nutshell: yes, people use the terms sex and gender interchangeably but they do represent different things and "gender" can be pretty loaded.
Re: Sex vs. Gender
DS: 11/8/11 | 9 lb 7 oz, 22 in
DD: 5/22/14 | 9 lb 9 oz, 21.5 in
My intention in posting this was more of an "FYI - here's why we point out the difference between these words", not to scold anyone.