What happened to all of the apostles biological descendants if they were married and had children?

Some Christian sects claim all of the apostles were married and had children. That would mean Saint Paul, Saint Peter, had children, probably grandchildren. What became of their children? Why did they never appear in the historical record?
Update: You would think there be record like "oh yeah Saint Peter's son moved to Corinth and became a laborer". We don't see any mention of biological children. It's like the apostles were celibate according to the historical record
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