The director of a new biopic about the celebrated fossil hunter Mary Anning has defended his film after criticism of its lesbian romance storyline.

Ammonite, which stars Kate Winslet and Saoirse Ronan, recently began filming in Lyme Regis, the coastal town in Dorset where Anning lived in the early 19th century. Anning never married and is not known to have had any direct descendants, but a report in the Telegraph suggested her distant relatives were at odds over the film’s central relationship, a romance between Anning and Charlotte Murchison.

Barbara Anning was quoted as saying: “I do not believe there is any evidence to back up portraying her as a gay woman.” She added: “Do the film-makers have to resort to using unconfirmed aspects to somebody’s sexuality to make an already remarkable story sensational? This adds nothing to her story.” Another relative, Lorraine Anning, took a different view: “To be honest, it doesn’t matter; as long as it’s well presented and tastefully done and in the spirit of Mary Anning, then I think it’s brilliant.”

The film’s writer and director, Francis Lee, previously responsible for indie hit God’s Own Country, responded with a series of posts on social media. He wrote: “After seeing queer history be routinely ‘straightened’ throughout culture, and given a historical figure where there is no evidence whatsoever of a heterosexual relationship, is it not permissible to view that person within another context?” He added: “Would these newspaper writers have felt the need to whip up uninformed quotes from self-proclaimed experts if the character’s sexuality had been assumed to be heterosexual?”

Anning, who died in 1847 aged 47, is renowned for a series of discoveries she made while fossil collecting in the rock formations around Lyme Regis. As the poorly educated daughter of a cabinet-maker she received little official credit for her work during her lifetime; her reputation has steadily increased since.