It seems like many of the things we associate mostly with girls, and mostly with boys - may be inherently (literally!) true.
Studies seem to show that girls really do seem to talk before their male peers, and boys seem to walk before girls.
Added to that a boy's tendency to prefer action over faces and words, and a girl's preference for facial study and one-on-one conversation, and we may not just be stereotyping here.
There are many old wives tales that are blatantly false (think a full head of unborn baby hair causing heartburn) but many are based in fact.