Dozens of academics have voiced their concerns over the ‘choose your own sex’ question proposed for the 2021 census.
Under draft guidance for the “What is your sex?” question, the Office for National Statistics (ONS) will allow people to give their preferred option instead of biological reality.
More than 80 senior academics signed the letter to the census authorities, many from Oxbridge and Russell Group universities.
It read: “This will effectively transform the sex question into one about gender identity.
“We are concerned that this will undermine data reliability on a key demographic variable”.
Several of the signatories did not provide their names for fear of being labelled “transphobic”.
Dr Alice Sullivan, professor of sociology at University College London, said it is a “great shame” that a “chilling climate” is closing down debate on transgender issues.
The ONS said its guidance is “very similar” to what it provided over the telephone in 2011.
However, the academics stated that it is unknown how that affected the data collected.
Professor Heather Joshi emphasised the importance for accuracy as the census is “the gold standard for other basic demographic questionnaires”.
Draft census orders will be brought to Parliament next year.
The question about gender identity will be voluntary, while the question about birth sex will remain compulsory.