How do melosis and sexual reproduction (fertilization) produce offspring that differ genetically from the parents?

2 answers

First off, it is Meiosis, which deals with the reproduction of sex cell- mitosis deals with somatic (body) cells
okay now to your question. Each Parent carries a gene well not one more like 46 (somatic)but in Meiosis only 23. Each gene or Alleles which are traits or copies of that same gene are transfered in meiosis. A Dominant gene is an alleles that is carried more prominantly in the gene, example brown eyes is a dominant gene which is why more people have brown eyes. A Recessive gene is a alleles that is carried less prominantly in the gene (same scenario as the Dominant gene) but for example blue eyes is a recessive gene and that is why there aren't many blue eyed people. Now I'm sure your asking: How do you know what is Dominant and Recessive well a fellow by the name of Reginald Punnett a Pea Plant farmer came up with what is now known today as - you guessed it- the Punnett Square.
This is a simple graphical way to determine all the potential combinations of genotypes in everything living. (He used it to breed healthier taller Pea Plants) A Genotype is the genitic makeup of something or someone AKA Alleles. Im going to give you an easy example.
I have a Recessive gene Red hair.
I will have this as {rr} in the Punnett Square.
My b/f has a Dominant gene Brown hair. I will have this {BB} in the Punnett Sqaure.
Here is the the Punnett Sqaure set-up(imagine this as a grid) Put the genotype of one parent on the side and the other at the top,

[B] [r]
-----------------------------
[B] [ BB ] [ Br ]
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[r] [Br ] [ rr ]
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ok let my explain. [Br] represents that Brown hair is dominant over Red and visa versa. My grid shows that our children have a possibility of 25% completley Dominant [BB] brown hair gene 50% [Br] which shows that brown is dom. over red and 25% Recessive [rr] red hair. It basically shows that 75% of chance is our child will have brown hair and only 25% will have red hair.
Of course there are many possibilities my example shows the most easiest form.
I hope I answered your question; I know it is confusing but if you still don't understand google punnett square and most sites can help you better understand this.
the grid should be set us like this
B r

B BB Br

r Br RR

i don't know why it set up like it did but it should look like this