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Blonde hair in offspring

  1. Sep 14, 2010 #1
    I have always heard that the recessive gene for blonde hair needs to be in both parents in order for it to pass onto the children.

    Yet, I've read of many cases where only one of the parents carries the gene for blonde hair and somehow the children end up being blonde.
     
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  3. Sep 14, 2010 #2

    Monique

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    What cases are you talking about?
     
  4. Oct 9, 2010 #3
    Well for example, I know someone who has natural blond hair but he has Native American heritage. I don't think it's possible for the Native Americans to have carried the recessive gene for blond hair so wouldn't have the recessive gene "canceled out" at the point in his family tree where his Native American ancestor mated with his white ancestor?
     
  5. Oct 9, 2010 #4

    russ_watters

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    The gene is what it is and stays what it is - if you get a blond and a brown gene from your parents, you have brown hair, but you can still pass that blond gene on to your kids. It may not be active, but it still exists and can be passed-on. It's possible for a couple of parents who have several generations of all brown-haired ancestors to have a blond kid.
     
  6. Oct 11, 2010 #5
    I understand that but what if one part of the family doesn't carry the recessive gene at all? Like in the case of my blond friend who has Native American heritage. When his Native American ancestor reproduced with his white ancestor, wouldn't the recessive gene be gone or is it possible that Native Americans carried the gene?
     
  7. Oct 11, 2010 #6

    lisab

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    No, the recessive gene doesn't disappear. It's not expressed, but it's still there. As far as I know there's no way of telling, by looking at physical characteristics, if someone carries a recessive gene. It's quite possible that somewhere in your friend's Native American heritage, there's a Swede hiding :wink:.
     
  8. Oct 11, 2010 #7

    russ_watters

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    I'm not following. Is one parent pure Native American? At what level are the Native American and white "ancestors" you are talking about? Parents? Grandparents? Great grandparents?

    It only takes one white ancestor on each side of the family - no matter how far back - for it to be possible for the blond genes to be there.
     
  9. Oct 12, 2010 #8
    His grandmother is a pure Cherokee. The rest of his ancestry is British.

    I initially thought that both parents need the gene for it to be passed on but from what I understand now, only one parent needs it in order for it to pass on but both parents need it for it to be physically expressed in their offspring. Am I understanding this correctly?
     
  10. Oct 12, 2010 #9
    That's right. You have two copies of each of your genes (possibly two different versions), one from each parent. Each parent picks at random which of their two copies to give when they have a child. To be blonde, you need both of your hair-color genes to be the "blonde" version of the gene. If only one of them is the blonde version, and the other is, let's say, the brown version, then you will have brown hair.
    So in order for you to be blonde, each parent needs to have had at least one blonde gene to give you. If only one parent has a blonde gene to give you, then you could still have the gene (and be able to pass it on), but you won't be blonde yourself because your other hair gene isn't the blonde version.
     
  11. Nov 2, 2010 #10
    So if two blonde parents mate, it's impossible for their child to NOT have blonde hair since both parents would not be carrying a brown version?
     
  12. Dec 22, 2010 #11
    I thought the gene for blonde hair was dominant and brown was recessive?
     
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