Question: Why are some people born with hair and some are not?

Keith Siew answered on 27 Jun 2013:

I would suspect that it has a lot to do with how well developed the hair follicles are… I suspect that in some babies they mature faster and begin to produce hair in the womb while others don’t…

The requirement for hair on the head is to trap heat (you lose the most body heat from your head)… and in the womb you’re kept warm by your mother so you don’t need a big mop of hair on your head as much… also it would get all messy and not make for a very good hairstyle on the way out of the birth canal… I don’t care how strong the hair gel is!!! Haha!

But when the baby is born because its so small… the volume to surface area is quite large compared to that of a fully grown adult so babies will lose body heat much faster… so it may be the results of evolutionary adaptation from our ancestors that lived in colder parts of the world… that being born with a full head of hair helped to protect the vulnerable baby from the cold and more likely to survive… and those genes have been passed down throughout the generations… hence why some are born with hair… and others not!