Mackellen identifies as an antinatalist, a philosophical movement based around the tenet that it’s cruel to bring sentient lives, doomed to suffering and to causing suffering, into the world. “Or at least I think our culture is very pro-natalist and it’s to our detriment. I would like to see us voluntarily reduce our population.” But cultural pressures, she says, drive people to have children by celebrating childbearing without acknowledging the consequences for themselves and the planet.

“My mum grew up thinking that getting married and having kids was what you did, but she raised my sister and me to not feel like those were our only options.” Her stance has posed no problems to her partner of 10 years, and many of those around her were congratulatory when she was sterilised. “I live in the liberal [San Francisco] Bay area,” she says, “and I’ve always been really vocal about this.” However, she can’t always discuss her concerns about human population with friends, which is why she is part of a community called the Voluntary Human Extinction Movement, or VHEMT (pronounced vehement) for short. Despite the drastic-sounding title, the organisation welcomes those whose end goal isn’t necessarily human extinction, along with parents who have come around to the VHEMT perspective to some degree. The organisation’s literature is rational and often humorous in tone and, says Mackellen: “It’s nice to talk openly with people who have similar feelings and frustrations, like when I read the environmental news and think: wow, how could anybody produce a new human when the effects of humans are very obvious, I feel, and the situation is getting worse.”