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Trista Robichaud
Scientist. Biochemist. Jobseeker. Science Advocate. Postdoctoral Researcher. Educator. Explainer. Nerd Girl.
Scientist. Biochemist. Jobseeker. Science Advocate. Postdoctoral Researcher. Educator. Explainer. Nerd Girl.

Trista's posts

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Feb 2013 lab picture :)

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More Texas Flowers :)
April 22, 2012 (8 photos)
10 Photos - View album

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Plant Photos

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AllExperts Friday: Yes, Virginia, there's a 50% chance of blue eyes in your future...

I get variants on this question at least once a week in the genetics category. I'm slowly building a generic form letter as an answer. I'd appreciate feedback from my science readers on clarity and if I've said outright wrong things.

_Questioner: Expectant Mother
Subject: What will our baby look like?

Question (This week)

My husband and I are goofing off with our family members and guessing what our lovely little baby girl will look like when she is born. Both husband and myself have light skin. I have hazel green eyes, and hubby has blue. I have light to medium brown hair with an auburn undertone. Hubby has blonde hair, with red(almost orange) facial hair. His mom is a natural red head, and his dad has black hair. My mother has red hair, and my father has brown hair. I was born with jet black hair and hubby was born with strawberry blonde hair. Can you give us an idea of what our little girl will look like?_

Hello Expectant Mother! Congratulations on your pregnancy!

First, some quick notes on how inheritance works. When you make egg cells, your body takes all your genes, shuffles them like cards, and then deals out one-half a deck to each egg cell. Guys do the same thing with sperm cells. When a baby is made, your and your significant other's DNA half-decks are combined to make a full deck of genes for each child. The number of cards (genes) is fixed. However, the pictures on the cards are not 'one of two' pictures. Really, human inheritance has many possible pictures for each card number. We call different pictures in each card position 'alleles'.

But what about hair or eye color?

Human pigmentation is something we don't understand all that well yet genetically. If we imagine a person as a factory, there is a whole department in the factory dedicated to producing the two known pigment genes for skin and hair, eumelanin (brownish) and pheomelanin (reddish). There are also support staff that indicate when the pigment is produced, how it is delivered, and where it goes, as well as how much the workers make. All of these factors are also controlled by DNA variations and genes. What color we see at the end is a summation of the entire department's efforts, which could be ten or more genes for skin. It’s at least six for eyes. Also, the instructions on what to make varies over time given how old the person is. For example, most often people's hair darkens at maturity, then grays at seniority, but this is not a hard and fast rule.

It sounds like there's a lot of pheomelanin in your family. I'd be surprised if your baby didn't at least have some red in his or her hair. Beyond that it's hard to tell. Personally, I started out with black hair as a newborn, then faded to honey-blonde like my mother, then darkened to a milk chocolate brown in my 30s. My father started out white-blond and then darkened to dark chocolate brown in his late 20s. My mother remains honey-blonde. You never know. :)

There are six genes that pool together to make eye pigment; if you have very little pigment, you end up blue or gray. If you have lots, you get a dark brown eye. If you have hazel-green eyes, and your boyfriend blue, the rule of thumb is you have a 50/50 chance that any kid you have will have blue eyes or hazel eyes. This is because each child inherits three genes for eye color from each parent, and each gene is an on/off. it's largely - but not always - governed by how much total pigment is made. Blue is least pigment, while green or hazel is an intermediate amount. Usually these pigment genes assort together; it takes some unlikely combinations to produce green eyes. Lucky you!

Ultimately, genetics are funny. Your child may look like you, like your husband, like your father, or like his mother. Your baby will be a combination of you and your spouse's best qualities. You never know until you see it, so try to enjoy the mystery!

There's a lot to read out there. Hopefully what I told you makes sense. Please feel free to come back if you have more questions.

Why I'm pro-choice. "We (humans) have the right to make our own choices about our bodies."

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Huzzah for crowdsourced science! :)
Stop playing World of Warcraft and do something useful for a change! Did your mother just tell you that? You could go outside and enjoy the nice weather or you could continue to play a computer game but help scientists at the same time. Play Phylo and and align some human DNA sequences to mouse and the fruit fly. Don't do this if you are a Creationist as your head may explode.

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If you're in the US, please consider signing this petition to increase the NIH's yearly budget! Thank you!!/petition/increase-nih-budget-33-billion-dollars-next-fiscal-year-flat-307-billion-will-kill-jobs-and-hurt/2q2m6Rdc
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