Expert: Dana Krempels, Ph.D. - 2/10/2008

Question
hello :) i'm pregnant, and had a question about the genes i can expect my baby to inherit from the fathers side. my husband is pale, has blonde hair, blue eyes, and is overweight, but he has three siblings, all of which are thin, tanned, brunette and brown-eyed (and yes, they're all full siblings, not half!) so i was wondering whether the baby gets his genes, or the family genes. my husband takes after his father, where as the other three take after their mother, so i was thinking her genes are probably more dominant, but since my husband got the dad's genes, will they be more likely to be passed to my kid than the mothers? or doesn't it work like that?

Answer
Dear Stacey,

Your child will directly inherit the genes his/her father gives him/her, not the ones carried by his family members.

Blonde hair and pale eyes are recessive to dark hair and dark eyes, in general.  Your baby will inherit those genes from dad, no matter what his family members look like.  You don't say what your hair and eyes are like, so I can't comment on your contribution, but if you have dark hair and eyes with no family history of pale hair and eyes, the baby is more likely to be dark haired and dark eyed.

As far as weight is concerned, that is far more complex.  The tendency towards obesity is controlled by *many* genes, and is also affected by environment.  It is probably more important to teach the baby good eating habits than to worry about genetic tendency for obesity, since you won't really know if that's come along for the ride until the child is old enough to express such a tendency (which would not be likely to show up until s/he's a few years old, at the earliest).

Hope that helps.

Dana