So you've now learned why credentials are absolutely meaningless on internet forums such as this one? --- But yes, whether you choose to believe it or not, I am a biologist. I am also an accountant and a photographer, amongst other things.
No, I do not read and regurgitate USA Today for "my studies". I do not accept USA Today as a source of anything.
In the overwhelming majority of cases (iow, cases that don't involve any sort of rare genetic/chromosomal abnormalities), it is plain as day to tell between male and female. Even in such "rare abnormal" cases, it is usually quite easy to tell (the presence or non-presence of the SRY gene, for example).
So, in a simplistic sense, XX=female and XY=male ... This is a basic biological truth. Yes, there are some rare genetic/chromosomal conditions that have the potential to make this basic truth a bit more complicated in such extremely rare cases, but within the context of any "typical" situation (meaning, no genetic/chromosomal abnormalities), XX=female and XY=male.