Interview X-Men Companion 1982
I know interviews should be taken with a grain of salt...but there's an interesting piece of information that some of you guys have been harping on about and it turns out that according to Dave Cockrum back then in 1982 Storms mother was pregnant before she died.
COCKRUM: "I hadn't heard that. I don't know how many readers ever noticed, but when the plane fell on her house, her mother was pregnant. I've always had this little germ of an idea in my head that she delivered in the wreckage and that Storm has a brother or sister somewhere. Chris has always been reluctant to do anything with that idea."