Most Facebook executives didn't allow their own children on Facebook - according to Ms Wynn-Williams. "They had screen bans. They certainly wouldn't allow them to use the product."
And yet she says reports from 2017 - that the company had been using algorithms to target and categorise vulnerable teens - were true.
"The algorithm could infer that they were feeling worthless or unhappy," she alleges.
The company - which also owns Instagram and WhatsApp - could, she claims, identify when a teenage girl had deleted a selfie on its platforms, and then notify a beauty company that it would be a good moment to target the child with an advert.
Ms Wynn-Williams says she "felt sick" at the thought and tried to push back, "although I knew it was futile".
