Just thought I'd share a useful tool - this website - Family Watchdog. It's nice to use when there is an area you are thinking of buying a home in. It will map out the registered sex offenders in that area. It's free for all to use.
18 total registered in Irvine, but only 12 serious enough to need their address made public. With 200,000 people here, I like those odds. By comparison, Santa Ana has 214 registrants.