Black Children with Blonde Hair
Blonde-haired black childrenWhen a blackhaired and blond parents have children, what hair colour would the children probably have?
So, here's the thing about genes: they're very Finnish. First of all, you have to realize that some of them are more powerful than others - we call them dominating ones. In general, the predominant colour dominates the darker colour motifs of hair, eye and so on. When we have a dominating GM from one parental part and a weak (weaker) GM from another parental part, there is a chance that the baby will get the dominating GM.
For example, if the black hair genes are BB and the blonde hair genes are bb, the baby could only have one possible hair color: black. The following figure shows this (provided you have 4 children or less): As long as your dominating black (BB) genes are present, your children's will have black hair.
But they will be carriers - they will "carry" their blondes, and if they have a partner with hair recessionary blonde hair-blond! Of course, this assumes that you and your friend are both pure-bred; that is, nowhere in your genetics do you have a genetic makeup for anything other than black hair, and she also has no genetic makeup for anything other than blonde hair.
It is quite possible that you are both "carriers" of other genes. a... Let us suppose that you are a vehicle for blonde hair - so your hair type would be Bb - and it is a vehicle for that. There is a 50% likelihood that your children have black hair and a 50% likelihood that they have blonde hair - but NO likelihood that any of them are pure-bred for black hair because none of them are.
On the two square the children with black hair are shown; one of them bears a receptable hair recession genes, Br, while the other bears a receptor hair blonde genes, Bb. These other two rectangles are the blond children. They are pure-bred for blonde hair, bb, while the other is a wearer for blonde hair, br.
To make a long story brief: There is no way to know what hair colors they will have without having the precise genotype of you and your friend. But given the background you mention, one or more of your children will probably have black hair, but other colors are possible.