Question: "How come your son Jimmie isn't colorblind when his father is"
Wrong answer: "It some times skips a generations, maybe his kids will inherent it"
Right Answer: "it's on the X chromosome, he got his fathers Y chromosome, so his kids will not inherent colorblindness from his side of the family!"
Question: "How come your daughter Susie isn't colorblind when her farther is"
Confused answer: "It some times skips a generations, maybe her kids will inherent it"
Right Answer: "The confused answer is less wrong than with the son, it's on the X chromosome, she got her fathers X chromosome, so half heir sons will be color blind"
Simple genetics, your Mother has XX your father has XY, let's use little x to denote colorblindness, you get a random chromosome from each parent.
Colorblind father -> sons have normal vision, daughters are carriers:
xY + XX - > 50% XY + 50% xX
Colorblind mother -> sons are colorblind, daughters are carriers
XY + xx - > 50% xY + 50% xX
Carrier mother -> half sons are colorblind, half of daughters are carriers
XY + xX - > 25% xY + 25% XY + 25% xX + 25% XX
Finally if colorblindness runs in both families:
xY + xX -> 25% xY + 25% XY + 25% xx + 25% xX
both parents colorblind -> all children colorblind
Question: "Have you ever wondered, how does the xX females know not to use the color blind gene?"
Answer: "They do not, half the relevant cells in their eyes will have a bad photo receptor... but the brain is pretty smart, it quickly learns to boost the signal from the other half of the cells"
Warning: The above is strictly only true for X-linked dominant diseases such as colorblindness, a similar approach can be used to elucidate the inheritance pattern of Classical Mendelian traits, but does not work for complex trait such as height which is influenced by multiple genes.