[jedberg]

It depends if you mean SF or are including the surrounding area.

The few people I know with kids in SF proper are either dual-income or did well on a startup. Some people live in the Sunset, which is more suburban -- still expensive but at least a little more kid friendly.

Most everyone else I know leaves the city for a suburb. Essentially having kids means your commute gets longer!

(Although in my case it actually got a lot shorter because I also got a job a lot closer to home in the South Bay instead of working in SF).