“In some ways, when you have that many bad things happen, it’s a sense of disbelief,” she says. “This was one of those situations where there’s two aspects. A divorce and the F.D.A. There was no workaround in either. So it was one of the first times in my life where you have to accept, you have to actually change. Like, I need to come up with a different way of approaching both of these relationships.”

Mr. Brin is fortunate that Ms. Wojcicki is not the vengeful type. Once they learned, from his spit test, that he has a rare genetic mutation that increases the risk for Parkinson’s disease, she bought the patent on a gene variant that could protect people who have that Parkinson’s-related mutation.

As Vanessa Grigoriadis wrote in Vanity Fair, the love triangle that ended Ms. Wojcicki’s marriage was analyzed in different ways in Silicon Valley. To some, “it’s about the danger inherent in data sets, when the data includes too much information about one’s mortality. If Brin had never learned about his Parkinson’s risk, he might never have had what a friend of the couple’s characterizes as an emotional crisis and strayed from his wife. (But had Wojcicki not helped him discover his risk for contracting the disease, he might not have enacted the healthy lifestyle choices that may prolong his life.)”

Ms. Wojcicki says that after the separation, she felt like she had entered another dimension, comparing it to stepping through Harry Potter’s Platform 9¾. “It’s a crazy world and you never knew it existed until you enter it,” she says. She tried reading a book about divorce but stopped when she got to a story of a divorced man whose ex-wife came over and chopped up his new girlfriend’s underwear.

“I was like, ‘I never want to be one of those people,’” she says. “I never want to be angry. For me, it’s a lot of work. I can be angry for 24 hours and then I’m just like, ‘Well, let’s just be friends.’”

It is a sentiment echoed by her mother.

“My theory is that you’re only hurting yourself when you’re angry and revengeful,” Esther Wojcicki says. “I was mad at Sergey for what he did. But I don’t carry grudges. He’s the father of my grandchildren. He was not such a good dad when the kids were babies. But he’s a very good dad now. He made his own life difficult, unfortunately. I can still be civil to him. Why not? What’s in it for me being nasty?”