Kate Middleton, like anyone diagnosed with cancer, has had a tough year. After announcing she had completed chemotherapy on May 9, she is gradually returning to royal duties as she continues to recover — and one royal biographer claims that faith has been part of her cancer journey.

Updated version of Robert Hardman Charles 3: The New King. New court. The Inside Story (serialized in The Daily Mail. 2), the author writes about issues of religion and how they affect members of the royal family at different levels.

While King Charles is well known for his support of the "steadfast devotion of the late Queen" to the Anglican Church, Hardman shared that Prince William did not have the same "interest in faith and spiritualism" as the king. Even though both his wife and father were diagnosed with cancer this year, Hardman said one source told him there was "no change of course" in terms of William's religious beliefs.

An insider told the author that the Prince of Wales "is a modern young man and I think he is perplexed by certain aspects of rituals and religion."

However, according to "Friends going to the family church," the Princess of Wales seems to share a different opinion from her husband following her recent cancer diagnosis. "I would say things are more hopeful," an insider told Hardman, referring to her interest in mental issues.

The biographer said that Princess Kate "is said to have become quite interested in the question of faith as a result of her condition."

And although Prince William is not particularly religious, the book argues that "when the time comes, he will comply with all his constitutional obligations to the Church of England in his role as King." That's why the public should not expect William to "suddenly become a regular admirer or pretend to be a zeal for something he doesn't personally feel," Hardman added.

As for the Princess of Wales, Hardman delved into the "crazy" conspiracy theories surrounding her absence from public life before her cancer diagnosis was announced to the world. Citing an aide to King Charles, he noted that "the Princess of Wales has no constitutional responsibility and will never do so," so the Welshman decided to wait and publish the information when he was ready.

"She plays an absolutely important supporting role in raising children who are in the line of succession with the Prince of Wales," the source added. "But she herself is not. Her situation is different and it can be treated differently."