Briefly, a study was being conducted to compare how learners of French as a second language were learning the gender of words. In order to compare their progress against native speakers of French, they tested 17 adults and 42 teenagers with a list of 93 masculine and 50 feminine nouns.
To the researcher's amazement, the native speakers were not only far from 100% correct, there was considerable disagreement between adults and teenagers.
Most commenters have expressed surprise at the low agreement between adults and teenagers, but most also point out that among these particular words some are especially difficult or formal words that adults might be more likely to use.
A further point is that oasis and primeur, although originally feminine, do now have common masculine forms. Oasis is a drink and primeur is used as "en primeur", first of the crop more often than the feminine form, a news scoop.
The two words that the teenagers knew best were "cible", target, and "victime" which one commenter thought could be significant. Another though pointed out that "La Cible" is a television programme.
I have been finding the discussions fascinating, especially because I seriously thought French children were so well drilled in their language that it would be inconceivable that there should be errors of this sort. Additionally I had no idea that the gender of a word could change over time as is apparently the case.
I have always thought that people who learn a language by assimilation, and are prepared to have a go, end up much more fluent even if not always grammatically correct, whereas people like me hesitate while making sure verb endings and noun genders are correct. Clearly it has largely been a waste of my time learning grammar because even French people get it wrong! See, Miss Howcroft!