I've lived in a city for several years where I have met disproportionate numbers of people acting like (stereotypical) ESFPs and possibly ESTPs. I very much doubt that all of them are. Many, sure, but I am certain that many other types are represented. What they do all seem to have in common is a desperate desire to fit into the group. Some of them act quite differently when away from that group. It has to do with the environment they've put themselves in and where they are in life. Same sort of thing, I think.
I'm not saying it's strange to have an SJ parent, by the way. I probably have at least one, unless my dad actually is an INFJ. I do find it strange though that so many people claim to have xSFJ moms when the types of other family members seem quite widely distributed. There aren't even as many ESTJ dads as I would have thought. Plenty of people claim to have F dads, for instance.