Jump to content

How to calculate the probability of hair colour of a child


Recommended Posts

Hi all,


I would much appreciate if somebody could point me in the right direction to working out a few simple things about a child based on it's parents and maybe grand parents features. I would like to start with something simple like hair or eye colour, height or whatever is easiest (hair would be best if possible).


So if someone could explain how to work it out and back it with some links to formulas that can be understood by a regular person that would be great!


The scenario would be, e.g:

man with blond hair + woman with dark hair = what is the most probable hair colour for their child and what is the probability.


Then to narrow it down (complicate it) we could add grand parents:

on male side grand father (his father) with blond hair , and grand mother with red hair

on female side grand father (her father) with dark hair and mother with blond hair.


What I'm looking for is the formula more than just working out this scenario above. I'm finding lots of formulas like that for diseases but not for normal hair, eye, height things. I thought we used to do that at school a while ago (I'm from Poland) but forgot how to do this.


I would much appreciate any help with this,


Many thanks,



Link to comment
Share on other sites

You'd need to know a lot more than just what a child's parents' hair looks like to give any sort of accurate probability. You need to know information about their genetic makeup, which information on the grandparents may help with but not enough to fix the problem.


As an illustration, even if we simplified the issue of inheritance down, your results would look like this:


Blond + Brunette = 50% chance of being blond/50% brunette or 0% chance of being blond/100% chance of being brunette.


Based on the grandparents information, it is more likely to be a case of 50/50 blond/brunette, but again, that's assuming gross simplification of how hair color inheritance works.

Link to comment
Share on other sites

Ok time for a punnet square:)

DAD'S GENOTYPE (Red and blonde)

RED ......| BLONDE|


Strwbry |BLONDE |BLONDE MOMS GENOTYPE (Dark and blonde)




Overall, its a 25% chance the kid will be a strawberry blonde (Reddish-Blonde hair with freckles)

25% chance of brown (Dark or light) With freckles (has red hair gene)

25% chance of brown (Dark or light) Without freckles

and 25% chance pure blonde

Those with red hair gene may have reddish highlights in the sun and probably light skin and freckles

sorry for crappy square..

Edited by paulk27
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.