The couple use they/them pronouns for baby Anoush to protect them from gender bias. (BBC)

A UK couple have decided to keep their baby’s biological sex a secret, even from their family, to protect them from unconscious gender bias.

Hobbit Humphrey, 38, and Jake England-Johns, 35, are circus performers and members of Extinction Rebellion, and are raising baby Anoush on a houseboat near Bath.

The parents use they/them pronouns for their child, and England-Johns told BBC’s Inside Out West: “Anoush is the most lovely little human. They’re into everything, they’re really active — just a delight.”

He wants to make clear that their definition of gender-neutral parenting is: “Us trying to behave neutrally to our child, rather than trying to make them neutral. Everything’s on the table… it’s all very much up for grabs.”

Humphrey added: “Eventually they will get told by somebody that pink is only for girls and blue is only for boys, and you can’t play with that because you are a particular sex.

“That’s still a thing that happens these days. We’re just trying to protect Anoush from that… There’s just a bit more of a balance that I think needs to be there, so that we show kids that whatever it is that you’re interested in is OK.”

Anoush’s grandmother said she is “glad” to have learned to use they/them pronouns.

They have experienced resistance to their parenting choice, especially from family. Humphrey said: “My mum was pretty surprised at first, she didn’t understand why we were trying to do this.”

Humphrey’s mother, Camille, told Inside Out West that she eventually found out the baby’s biological sex when changing their nappy after 11 months, but that she’s keeping the information to herself.

She said: “It was a struggle… It’s a learning curve. I grappled with what to call them, and hating when I slipped into ‘it’, and then changing between sometimes calling them ‘he’ and sometimes calling them ‘she’, finding it difficult to get the ‘they’ business.

“But over time, as with any learning, it became embedded and they became ‘the..’ And actually I am so glad I’ve had this experience.”

This year, the woman who held the first gender reveal party said she had “mixed feelings” about the trend she started.

She said: “Assigning focus on gender at birth leaves out so much of their potential and talents that have nothing to do with what’s between their legs.”