But there are female weight lifters. You mean they probably only started later in life, and they would be as strong as men if they started at 6? Not sure if weight lifting is even recommended for kids, what is the average starting age?

Also, I googled and a lot of the best female weight lifters look Chinese. I have a suspicion that they might be recruited by the Chinese system at early age and pushed for the glory of China, at the expense of their health. So cultural norms wouldn't be the issue here.