Expert: Sophia Jane Carter - 1/21/2008

Question
I'm sure you get this question a lot, but when combining my own genetics with my husbands, what is the most possible outcome?  I have medium brown wavy/thick hair, blue eyes, fair skin, and I am 5'6".  He has very dark brown (almost black) straight/fine hair, hazel eyes, fair skin, and he is about 5'9". As for my parents, my mom has straight/fine medium brown hair, medium skin tone, hazel eyes, and is about 5'3".  My dad is Native American and has wavy/thick black hair, medium/dark skin tone, hazel eyes, and is about 6'1".  For his parents, his dad has blue eyes, very dark brown straight/thick hair, medium skin tone, and about 6'1".    His mom has brown eyes, medium brown straight/normal hair, medium skin tone and is about 5'3".  Whew!  That wore me out, haha!  Thank you very much for your time.

Answer
Thanks for the question, Emily!  It's normal to wonder what your children may look like, but the specifics  can get quite a bit convoluted.  I'll try to make this as intelligible as possible!

Eye Colour

Eye colour is probably the easiest trait to handle. All humans have a general gene for eye colour, but the particular variety of genes that you have (alleles) determine what your eye colour will be.

We recognize three prime eye colours in humans:  brown, blue, and green.  Brown eyes are dominant.  Blue eyes are recessive. Green eyes are a melanin intermediate. The trouble with eye colour arises when you get intermediate colours like green, or more subjective colours like hazel; what some would define as hazel others see as green and still others would classify as brown.  This makes it difficult to work out exactly what alleles went where.  I will assume that hazel eyes are a case of incomplete dominance of the dominant brown allele (B) paired with the recessive blue allele (b).

mother1:  bb (blue)
father1:  Bb (hazel)
you:  (blue)

mother2:  BB (brown) or Bb (heterozygous brown)
father2:  bb (blue)
husband:  Bb (hazel)

Based on this, any offspring you have will have a 50% chance of having the Bb genotype (hazel, but also possibly green or some shade of brown eyes), and a 50% chance of the bb genotype (blue eyes).

If I may throw in an interesting fact:  green eyes are the rarest eye colour in the human species!

Hair Colour

There are two types of pigment that determines hair colour:  eumelanin and pheomelanin.  From these two types of hair melanin there are also three subtypes:  black (eumelanin), brown (eumelanin), and red (pheomelanin).  The higher the concentration of eumelanin the darker the hair. Pegging down an exact probability is difficult, because the spectrum of hair colours depends on concentrations of hair pigments.  Since both you and your husband have dark hair, and both of your biological parents have dark hair, it's very likely that any offspring you have will have hair colour ranging from black to medium brown, although it is possible to for any children you produce to have lighter hair if your biological grandparents were blond(e)s or redheads.

Hair Texture

Hair texture is determined by the shape of the hair follicle.  If you were to take a cross-section of the hair follicle you can see the shape it creates.  A round cross-section corresponds to straight hair, while an elongated/oval cross-section produces curly hair.  Wavy hair is in between.  Based on your pedigree, your children will likely have slightly wavy or straight hair.

Skin Tone

Skin tone is inherited in a similar fashion as hair colour.  Based on your pedigree, your children will likely be fair skinned, but could also be medium toned.

So there you have it.  Whatever outcome, I'm sure you'll have gorgeous children!