Honestly, I don’t feel that there is any specific reason. I don’t think it’s like boys are more bold than girls or anything like that, I think that it’s just random chance and there just happens to be more boys who speak up than girls. If that isn’t it, then I don’t know why the boys spoke up more than the girls.
Yes, perhaps it is just a coincidence! I don’t think we can identify a specific reason, unless the individuals involved actually tell us their motivations.
It’s possible to observe a pattern or a behavior, and wonder/theorize about why it is so, but not have a scientific answer or fact to explain it.