I agree that socialization is the real key here. And, genetics does play a role also. Fearful parents will produce off spring that drift towards a fearful nature. How much socialization can overcome a genetically fearful nature is of constant debate amongst professional dog trainers.
I'm not sure that one can truly base friendliness based on breed alone, however, as within breeds certain "lines" tend to be more friendly than other lines. Fearfulness is common, unfortunately, in my breed - the Shetland Sheepdog. However exceedingly friendly and outgoing lines produce wonderfully happy, friendly dogs - both male and female.
So is friendliness more common in males than females generally? I'd say no. How a dog is socialized and how a dog is trained (ie. punishment based training vs. positive training) will much more determine friendliness and genetic family lines will also play a role.