Can a Child Have Different Dna From One Parent

-A graduate pupil from New York

October 22, 2014

First off, each child will pretty much get the same number of genes from dad. Boys and girls will get a slightly different set but these genes won't affect the sort of traits you lot are talking about. And all the sons will become the same number of dad's genes and the same goes for all the daughters.

So getting fewer or more genes from a parent is not the reason that a child favors that parent. Instead, it has to exercise with the versions of each gene you lot become from each parent and what traits that combination will give.

This means that under some circumstances, each child will have a really good chance at favoring dad while in others, they'll have a amend chance of favoring mom. And sometimes a kid won't favor either and may look more like an uncle or an aunt or different from anybody else in the family. That is the beauty of genetics!

Considering of this information technology is very difficult to predict beforehand which parent a kid will look like. You accept a better shot at making some predictions if y'all know each parent's DNA but fifty-fifty then you can just make predictions. You lot might be able to say the kid has a fifty% take chances of having dad's red pilus or a 25% chance of having his blue optics.

What I thought I would do to effort to illustrate this betoken is to give an instance of 2 parents and go over a few scenarios where the genes work out and then that one parent is favored and some other where a blend of the two is favored. Then I'll get over a third where the child doesn't favor either parent.

Genetics 101

In our examples, I volition focus on a ruby haired, blue eyed mom and a brown haired, brown eyed dad. As you'll run across, in some cases all the kids will expect like dad and in others, they'll come out looking like dad, mom, or a combination of the two.

Before seeing how these are all possible, nosotros need to accept a step back and practice a quick review of genes and how they work. Don't worry, this volition exist quick…

First off, we have two copies of each of our genes, i from mom and one from dad. And then we have ii copies of the gene that can pb to red pilus and ii copies of the brown/blueish centre color factor. (As y'all'll see later on, eye color is more than complicated than this.)

What makes each of us dissimilar is not that we have dissimilar genes but that we accept different versions of the aforementioned genes. So for instance we all have the MC1R gene merely some of us have a version (or every bit scientists call it, an allele) that can requite red hair and the rest of us have a version that won't give crimson hair. Something similar happens with heart color too.

OK, since we have ii copies of the MC1R gene and it comes in two versions, nosotros tin each have any of three possible combinations of this cistron. To brand things simpler, when I prove the combinations, I volition represent the non-scarlet version with an R and the ruby-red version with an r.

And then here are the three possible combinations:

• RR  Non red
• Rr       ?
• rr      Cherry

The hair color of two of these combinations is obvious and so I accept included them. Someone who is RR won't have red hair and someone who is rr will.  The catchy 1 is people who have ane of each, Rr people.

Turns out that for the near part, Rr people do not have cherry pilus. That is because not having red hair is ascendant over having carmine pilus. Some other style to say this is that red hair is a recessive trait. So here are the three combinations again:

• RR   Not red
• Rr    Not carmine
• rr      Scarlet

Chocolate-brown and blue eyes piece of work similarly in that brownish optics (B) are dominant over blue (b). Which of course means that blue optics are recessive. Then BB and Bb people accept chocolate-brown optics and bb people have blue.

At present we are ready to look at our two parents and their kids. Every bit yous'll see, each parent's hidden, recessive genes affects the chances that a child will await like a parent.

Favoring Ane Parent or Being a Blend

Imagine a ruddy haired, blueish eyed mom and a brown haired, dark-brown eyed dad.  From this nosotros know what genes mom probably has. Her red pilus means she is rr and her blue eyes hateful she is bb.

Dad, though, is trickier. He can be whatever of these four possible combinations:

• RRBB
• RrBB
• RRBb
• RrBb

All four of these people would accept brown hair and brown eyes because they all have at least ane R and ane B. Merely the chances of favoring dad, instead of our red haired, bluish eyed mom, vary with each.

Let'south first imagine the RRBB dad. Recall that each parent passes only i copy of each of their genes to each child. This dad can but laissez passer an R and a B because that is all he has to give.

Our red haired, blueish eyed mom can only pass an r and a b for the aforementioned reason. This ways that every child will be RrBb—they will all have brown hair and brown eyes. They will all favor dad.

If we instead look at an RrBb dad, so nosotros can get completely dissimilar results.  In this case dad tin can pass either a B or a b and either an R or an r. This leads to four possible children:

• RrBb   Chocolate-brown hair, brownish optics
• rrBb    Blood-red hair, brown optics
• Rrbb   Dark-brown hair, blue optics
• rrbb    Red hair, blue optics

(Get to the end of the commodity if y'all are interested in seeing how I figured this out.)

Now each child has a 25% take chances of favoring dad, a 25% risk of favoring mom and a fifty% take chances of beingness a blend of the 2.

Depending on dad'southward genetic combination, the children tin all favor dad or only some can favor dad. The other possible genetic combinations or genotypes each have a 50% chance of favoring dad and a 50% chance of beingness a blend.

Of course, the same would exist true for a cherry haired, blue eyed dad and a brown haired, brown eyed mom. Except that there would exist some cases where mom was always favored.

And Now For Something Completely Dissimilar

Then far we have focused on a child favoring one parent or existence a blend of the two. It is likewise possible for them to exist dissimilar from both parents. For this I will focus on eye color only something very similar happens with pilus colors other than blood-red.

Eye colour is a flake more than complicated than I have painted here. At its simplest, there are actually ii eye colour genes (and this isn't almost complicated enough to really explicate eye colour).

One cistron is the one we described that comes in ii versions, brown and blue. Simply in that location is a second 1 that also comes in ii versions, light-green and blue.

The two genes are related in that dark-brown is dominant over green, and blue and green are dominant over bluish. Which likewise means blue is recessive to green, and blue and green are recessive to brown.

That was probably confusing so here is a table of each of the possible gene combinations and the color optics they would take:

As you can run across, whenever there is a B you lot accept brown eyes. When there is a G but no B yous have green optics and if you only have b'southward, you have bluish optics.

Allow's become back to our original example. Mom has blue eyes and and so is bbbb. Dad can exist whatsoever of six possible combinations but allow'due south say he is BbGG.

In this instance, each child has a 50% chance of getting a B and favoring dad and a 50% hazard of getting a G without a B and favoring neither parent. The kid would have green eyes fifty-fifty though the parents have brown and blueish. If grandma had green eyes, we'd say that the child favors grandma and not the parents.

Now imagine calculation more and more genes, each with their own dissimilar versions. Maybe the parents have wavy hair and the child ends upward with straight hair, maybe our chocolate-brown haired dad and red haired mom take a blonde kid, maybe the child has dad's nose, peradventure…

As y'all can encounter, things go messy fast! A child volition not always favor one parent or the other, it depends on each parent's genetic combinations. And a bit of chance nearly which genes happen to get passed on.

Figuring Out Pilus and Center Colour Combinations

To figure out why nosotros got the results we did with an rrbb mom and an RrBb dad, we need to suspension out the old Punnett square. In a Punnett foursquare, we make a table where all of the possible combinations of alleles that dad can laissez passer down are put along the superlative and mom's possible combinations are put along the side like so:

Mom has only one combination she can pass on, rb, and dad has 4. Y'all then match up each box and go the, in this example, four possible combinations:

Click hither to larn more about Punnett squares.

By Dr. Barry Starr, Stanford Academy

dyettbarathand.blogspot.com

Source: https://genetics.thetech.org/ask-a-geneticist/favoring-one-parent-over-other

Share this post