A family tree shows how members of a family are related to each other through a drawing or chart. The document discusses a trait called "left thumb over right thumb" that is inherited in an autosomal dominant manner, meaning if you receive one copy of the dominant gene (A) you will have the trait, even if you also receive one copy of the recessive gene (a). The family tree shows how this trait has been passed down through generations with those having the AA or Aa genotype exhibiting left thumb over right thumb.

1. By: Carlos San Martín Fdez.

2. What is a family tree?
 A family tree is a drawing or chart that shows how the
different members of a family are related to each other.
What is my trait?
• My trait is “left thumb over right thumb.”
Autosomal dominant inheritance

3. (Me)
aa
Aa Aa Aa
Aa
Aa
Aa
Aaaa
aaaa aaaa
aa
aa
Left Thumb over Right Thumb (AA, Aa)
Right Thumb Over Left Thumb (aa)