• A pedigree is a chart of the genetic history of a family over several generations.
• Males are represented as squares.
• Females are represented as circles.
• Shaded symbols signify that the individual is affected by the condition.
• Unshaded shapes signify that the individual is unaffected by the condition.
• A horizontal line between man and woman represents mating and resulting children are shown as offshoots to this line.
• Generations are labeled with Roman numerals.
• Individuals are ordered best on age. Oldest to the left, and youngest to the right.

 \n

Autosomal Dominant -

• If both parents are affected and an offspring is unaffected, the trait must be autosomal dominant (parents are both heterozygous).
• All affected individuals for autosomal dominant must have at least one affected parent.
• If both parents are unaffected for autosomal dominant traits, all offspring must be unaffected (homozygous recessive).

 \n

Autosomal Recessive -

• If both parents are unaffected and an offspring is affected in autosomal recessive, the trait must be recessive (parents are heterozygous carriers).
• If both parents show a trait in autosomal recessive, all offspring must also exhibit the trait (homozygous recessive).

 \n \n

X-Linked Recessive -

• If a female shows a trait in X-linked recessive, so too must all sons as well as her father.
• An unaffected mother in x-linked recessive genes can have affected sons if she is a carrier (heterozygous).
• X-linked recessive traits tend to be more common in males.