1. Pedigrees
A pedigree is a diagram of family relationships that uses symbols to represent people and lines to represent genetic relationships.
In a pedigree, squares show males and circles show females. Horizontal lines connecting a male and female show mating. Vertical lines extending down from a couple show their children. Subsequent generations are written underneath the parental generations.
it is customary to shade in the symbol of all individuals that possess the trait of interest.

2. Royal family pedigree expressing the hemophilia allele

3. My pedigree shows that:
The allele for Huntington’s Disease is:
Sex linked on the Y
Sex linked on the X
Autosomal dominant (caused by a dominant allele)
Autosomal recessive (caused by a recessive allele)

4. Sex-linked traits
22 of your 23 pairs of homologous chromosomes act the same regardless of your sex- autosomal.
The 23rd pair are sex chromosomes
Females are XX (inherit an X from each parent)
Males are XY (inherit X from mom and Y from dad).
Genes found on either the X or Y chromosomes are called sex-linked.

5. Sex-linked cont.
There are over a 1,000 X-linked traits; Y-linked traits are rare and mostly deal with sperm production.
In woman, a recessive allele on one X can be masked by a dominant allele on the other X.
In men, recessive alleles on the X are always expressed since there is not a corresponding allele on the Y.
This explains why woman are usually carriers of X-linked traits, but rarely express them.
For more info:

6. Autosomal Dominant For those traits exhibiting dominant gene action:
affected individuals have at least one affected parent
the phenotype generally appears every generation
two unaffected parents only have unaffected offspring
The following is the pedigree of a trait controlled by dominant gene action.

7. Autosomal Recessive For those traits exhibiting recessive gene action:
unaffected parents can have affected offspring
affected progeny are both male and female
The following is the pedigree of a trait controlled by recessive gene action.