Julia struggled to reach an accommodation with Darwinism for well over thirty years. As long as her uncle was alive, she avoided an open attack on him, clinging to the hope that he was more open to religious feeling than he was willing to admit. She, unlike her sisters, walked with pride in the family procession at his funeral in Westminster Abbey but grew increasingly restive over the Anglican establishment's readiness to promote Darwin to secular sainthood. Her frustration at this downplaying of the impact of his ideas erupted when Frank Darwin published a biography of his father. Darwin, she wrote in a review of it in the Spectator, had been ‘a destroyer’. Only as thoughtful Churchmen like Aubrey Moore found a new basis for reconciling Darwinism with religion did Julia rediscover her original excitement about the promise of her uncle's discoveries.

By contrast, her relationship with Emma Darwin remained remarkably stable. They understood each other well. Emma was readier to make allowances for her niece's singularity than most in the family. She respected Julia's determination to make a career for herself as a writer and set up her own household. As Julia wrote just after her death, she had a ‘wonderful power of […] always remembering that I was I’ and giving ‘what I wanted’.

Darwin could be less tolerant. Once out of his study, he wanted only to relax, strolling up and down his Sand Walk, playing backgammon with his wife or sitting absorbed as she read aloud some trashy novel with a pretty heroine. Talking about metaphysics into Julia's ear trumpet was wearisome by comparison. Even old Aunt Elizabeth, who had moved to live close to the Darwins in 1868, chafed under the need ‘to keep down trivialities & gossip’ when her niece was a guest. Emma's first duty was to protect her husband. She told Etty about his gloom one Sunday afternoon in 1870 when the doorbell rang and he feared it was Snow. He brightened up immediately when the statistician William Farrer was announced, who had come to discuss the grim subject of how far the Census might throw light on whether cousin marriages were as harmful to their descendants as Darwin feared. This was much more agreeable than talking about whether Origen was an Epicurean or a Platonist and why it mattered.