My niece had this as a toddler . she has amazing legs now ,( shes 36 now ) her mum had the condition looked at and the hospital said itd correct itself , it did thankfully , why not make an appointment at your docs for a referral to the hospital to put your mind at rest ..... good luck x
Could also be the footwear they are wearing. When one of ours was young he wore boots which pushed his legs out. Once we switched to proper shoes they soon fixed themselves.
Yes, boxy, I do know a cat is not the same as a baby. They are smaller, furrier, cheaper to keep and catch more mice. I would strongly advise giving birth to kittens instead of babies in future.