A daughter of French first lady Brigitte Macron testified Tuesday in the second and final day of a cyberbullying trial in which 10 defendants face prison terms of up to two years for propagating false claims online, including the conspiracy theory that she was born a man.

Ten people went on trial in France on Monday, accused of the online harassment of Brigitte Macron, who has been hounded for years by rumours that she was born male.

The video was like a flame to touch paper, fanning rumors across the internet, to eventually be picked up by U.S. influencer Candace Owens, who is the subject of a separate defamation lawsuit launche...