HET X HET......what does this mean? The term "Het" is short for Heterozygous.........."Het" means that your snake is carrying a gene for a simple recessive trait. I will use the simple recessive trait of Albino for this entire example. How does one become a het? When a Homozygous snake ( Albino = mm ) is bred to a normal snake ( Normal = MM )........all the offspring produced will be normal looking AND "Het" for the Albino gene ( Het = Mn ) You can only produce an entire clutch of offspring that are 100% het for a simple recessive trait if one of the parents is Homozygous for the trait.........meaning........it is visibly an Albino or a Piebald..........or an Axanthic.......or any other trait that is simple recessive. If you are working with a PROVEN GENE......then you know that you will be producing heterozygous offspring. But you may be working with your own "Dinking around Project"........in this case.........you will assume that you are producing het offspring in hopes to prove the gene yourself...........and boy is that fun!!!........Simply put........."hets make the world go round".......Producing hets and breeding them back together is how new mutations are proven and how breeders make the almighty MORE!!!!

By producing hets and breeding them back together and to the parents........this is how a trait is proven to be inheritable. The gene must be bred back within itself to prove that it is an inheritable trait and that it is simple recessive. Only when you see baby offspring that look just like the Homozygous mother or father can you scream.........."It's Genetic"

M = Normal Gene
m = Gene carrying the Genetic Trait we're after, In this case I'm using the Albino gene as example

WHAT :

• MM = Normal Animal
• Mm = Heterozygous Animal
• mm = Albino

RESULTING OFFSPRING:

• 25% Normal = MM
• 50% Heterozygous = Mm
• 25% Albino = mm

OK........now you have read what all this HET X HET stuff means..........and you see this square......so what does it mean?

We will work our way from the top:

M = Normal Gene: The "capital M" represents the normal gene.........meaning that this is a normal gene..........with no bells or whistles.
m = Gene carrying the Genetic Trait: The "lower case m" represents the Albino gene........this is the gene we are after.........we love the lower case letters......:)

WHAT : This is where our gene pairs are listed under............."What" basically means........what genes are represented by the square. In this case.........what genes do we have?...........we have MM.......that is a double capital "M".......why are they double??.........They are double because the genes are paired......this is called alleles. ALL genes will be presented this way....."in pairs".

Getting back to the MM.......this is representing a snake that has normal genes..........this means as far as you know, the snake is normal. So now we know that a normal snake will always be represented as MM that is a double capital M.......but it really can be any letter........just as long as the normal gene is shown in capital letters..........got me?

Now we have Mm........this is a capital "M" first.........and a lower case "m" second. This represents a Heterozygous snake........a gene carrier..........remember how the genes are "paired".........well check out what a Het's "What" looks like...........it has the capital "M" first and the lowercase "m" second...........why? Because it is not normal anymore.......if it were normal, there would be no lower case letters......it may look normal...........thats why it still has one capital "M" first..........but that sneaky little lower case "m" second means that it is a het!!..........it's carrying a simple recessive gene.............so remember..........when capital and lower case letters are in the same pair............your dealing with a heterozygous snake. The same applies for Double Hets........but that is another lesson...:).......and on another note........as long as you see a capital letter in the pair, that means your snake will still look totally normal ( I'm not talking about albinos het for this or that........or double hets......I'm talking about straight up regular hets! ) ........you need to get rid of all the capital letters.........that will be next!

Finally!!!!!!.........mm............this is representing a Homozygous snake.........the one you have been waiting for!! A double lower case "m" will always mean that the snake is homozygous ( visible ) .......it could be an Albino or a Piebald...........it could be what ever simple recessive trait you are breeding for..........Remember how the double capital "M" ( MM ) represents a normal snake.........that is normal looking............and that a capital "M" first and a lower case "m" second ( Mm ) represents a Heterozygous snake who again is normal looking and is carrying a simple recessive gene. So it just makes total sense that an Albino snake who is not normal looking at all is represented as mm..........it is Homozygous..........mm = Albino.........we knocked those upper case letters down where they belong!

So now that we have talked about everything that goes into the square.........lets see how the thing works? The square on this page is representing a HET X HET ( Albino gene as example ) breeding..........this we know is breeding a pair of normal looking snakes together that are each het for Albino ( Mm ) in hopes of producing an Albino!! ( mm ). First you have the square........it is three columns and three rows...........this is all you will need for a HET X HET square because we are only using one gene ( Albino )............when more genes are involved........then more columns and rows are needed.I will cover all that good stuff in future squares........not to worry. We are using the HET X HET example first..........and writing the most about it because it is the easiest to understand........and it is simple to look at.

To figure out the out-come of a HET X HET breeding using a Punnett Square you need to know the rules.............what is standard procedure?? Here is how it works. We know that a het is represented as Mm.Knowing this..........we now have to load our information into the square. This is done by using the columns and rows. What we are doing is breaking down the pairs of genes so that the square can solve the puzzle. The Mm is used in the first row at the top of the square, reading left to right and the first column on the left side of the square, reading top to bottom........I have these marked in green in the square below. You can see that the capital "M" comes first and the lower case "m" comes second. Nothing goes in the top left corner of the square.............your brain will probably fit in it when you are done....:).....mine sure will.

Mm =Heterozygous Animal

Above is how your square will look when you first start it. You have your Mm across the top reading left to right.........and you have it down the side reading top to bottom.

Now we are ready to fill in the blanks........I will do this step by step.

Starting at the top upper case "M"# 1in the left column you will combine it ( M ) with the top upper case "M"# 2 in the top row. This will make your first entry of MM in the square. Both are capital "M " and we know the genes are in pairs.........so the first entry reflects that pairing......which is MM........this example is below.

Next we start at the same spot using the top upper case "M" # 1 in the left column and combine it with the lower case "m" # 3 in the top row far right.This gives us our second entry to the square of Mm.......you always list the capital letter before the lower case letter in a square........this example is below.

Now we have the top row completed for the square.........it is in gray and it shows two entries.........MM and Mn.....so we have half of the square done so far.............this is shown above.

Next we move down to the lower case "m"# 4 in the first column on the left. We combine this lower case "m" with the upper case "M" # 2 in the top row.This gives us an entry of Mm.......notice that this is the second entry out of three on the square that is Mm.......and remember to always use the capital "M" first in the pairing. This example is below.

At last!!!........we are almost done the square..........now we go back to the lower case "m" # 4 in the first column on the left and combine it with the lower case "m" in the top row. This will create our final entry of mm.......which is in the tan square bottom right........now the square is complete and ready to tell us what the out-come of a HET X HET breeding is. There are four entries........three are in gray and one is in tan...........each entry represents 25% of the square.

Now that the square is done, we can determine the "Resulting Offspring". The square shows us one entry of MM, two entries of Mm and one entry of mm. We know that the square is broken into four parts that together equal 100%...........so each part must on it's own be 25%.

Lets break it down:

MM = 25% of the square
Mm = 50% of the square
mm = 25% of the square

So what do we have now?............lets break it down again.....remember the "What" way up top on this page?

• MM =Normal Animal ( 25% of the square )
• Mm =Heterozygous Animal ( 50% of the square )
• mm =Albino ( 25% of the square )

So our resulting offspring from this square is:

RESULTING OFFSPRING:

• 25% Normal = MM
• 50% Heterozygous = Mm
• 25% Albino = mm

Ball Pythons lay small clutches........so this 4 section square works nice when trying to put it into "egg terms".............simply put by using the above results............in four eggs.............1 baby will be normal ( MM = Normal )...........2 babies will be normal looking and het for Albino ( Mm = Heterozygous )..........and 1 baby will be Albino ( mm = Albino "Homozygous" )..........three of the offspring will look totally normal..........two of those three are HET............one of the three are normal ( not carrying the albino gene )...........those three normal looking snakes add up to 100% of the normal looking offspring. They each represent 33.3% of the total............so if the total is 100% and one of the babies is "Normal"...........that normal makes up 33.3% of the total and the two hets together make up 66.6% of the total..................this is why when breeding HET X HET..........all the normal looking offspring are called 66% possible het. You don't really know which ones are the "true hets"...........all you know is that two out of three should be a HET............so that is where the 66% possible het comes into play.............odds are in your favor!!!.........Simply put..........in each baby snake.........you have a 66% chance that the baby is carrying the albino gene.............and a 33% chance that it is not.

Maybe we should start calling them " 33% not possible hets"..........LOL............that don't sound very good...........:)

I sure hope this helps any of you who are learning about genetics, and for those of you who do know it all.............let me tell you..........this page totally sucked to write!!!!!!!!!

Off to the next section...............zzzzzzzzzzzzzzzzzzzzzzzzzzzzz