That would be reasonable. I personally knew of some that believed in Jesus until they died, their children didn't practice organized religion at all, and their grandchildren (my age) were/are athiest. Obviously, my observations are an extremely small sample size of families, but I highly doubt they were unique when we speak of the actual families impacted by this event.
My corporation has a facility in Israel, and I have worked with many Israelis. They probably would have (reasonably) skewed my observation and opinion if I would have known them well enough to ask similar questions, but the Holocaust and slavery are obviously very sensitive subjects that we just don't go asking people whose families were impacted it whatever questions we like, well at least most of us. That is the stigmatism that plagues us as a species I think.