Kurt Will was 42 years old when he packed in his career to look after his newborn.

At the time, he was working for Dow Jones on a fixed-term contract. The commute was grueling—a near-four-hour round trip—and his salary was practically the same as the cost of hiring a nanny.

Meanwhile, his wife had “the better career prospects” as an anti-trust in-house lawyer at Time Warner, he tells Fortune.

So it was “a pretty easy decision” for Will to stay home and raise his daughter—and two years later, his son.

He’s part of a growing number of fathers to take on the unpaid position of being a child’s chauffeur, nanny, cleaner, and personal cook—a role which historically fell firmly on the shoulders of mothers.