Here are some facts about salaries in the US:

• An additional 10cm yields a 3.3% higher wage
• Workers above average height earn 5% more than workers below average.
• The tallest quartile earns 13% more than the shortest quartile.
• Among monozygotic female twins, every additional inch(=2.5cm) of height is associated with a 4.5% increase in wages.

How can you explain this data? List down at least two theories as to what is the reason behind these observations. For each theory you write, think about what kind of data you would need in order to prove or disprove the theory