Pity that it is, (it was really hard to find a reliable source to prove this) because it would great to add to the page, however it's no longer accurent. For now, I will just display the information on here for those to view. According to the book Chris was 20 yrs. old when his parents passed and Claire was 15 yrs. old (1993) when their parents died. Here's a second source of information from the book that a forum had featured on their site, http://bbs.chinabroadcast.cn/read.php?tid=109739] which also confirms Chris' and Claire's parents' deaths. The book talks about events that happened before Resident Evil 1. (Original):

"Chapter One: Resident Evil 

Chris: Whenever the phone rings in the middle of the night. I know someone's dead who wasn't dead the day before. Happens all the time. Except when it's a wrong number. Like this totally drunk woman who thought I was her long lost lover. Or the idiot who tied up my line with a long monologue in Portuguese. 

I've had this late-night fear of the phone for five years now, ever since a state police chaplain called me at two a.m. to tell me my parents were dead. Their vacation van had been crushed by a runaway big rig. The coroner had to ID them through dental records, they were mangled so bad."