In my childhood, when the movie BMX Bandits (1983) [0] was super popular, helmets and any kind of protection did not exist. We did all kinds of crazy stunts, influenced by the movie. I don't recall any harmed kid among tens if not hundreds. Scaped knees and elbows - sure, but that's all!
Please ask Gemini to explain you that you cannot generalize over small samples like your two kids or a few dozen kids from your childhood…