Broodiness

[dardavis]

My five wheaten/blue wheaten hens that I hatched last year have all gone broody this year at about 13/14 months old.

Is this normal?

I was thinking perhaps one or two but all of them??

I also had one that hatched in January who at 6 months went broody.

Is this variety known for broodiness??

[Birch Run Farm]

I have two hens, one W and one BW.  Only the W went broody and hatched some chicks.  She is back to laying again and her chicks, while still small, have began pretty much taking care of themselves.

My curiosity is why some hens will care for chicks for a long time while others \'forget\' about them after a few weeks?