Big Headed Foals? Glitch Help!?

So I instanted baby-ed my mares in my new mustang herd and all the babies came out with humongous heads! I went into CAS and tryed to see if my Head Size Slider was the cause but it said the heads were normal and gave me the option to still go bigger! I'm guessing this must be a glitch or something. When I was in CAS I aged them up and they looked normal, but I need baby pictures for my stable! Please help or explain whats going on?