🧬 Rarest Trait Combinations
How Trait Multiplication Works
If green eyes occur in 2% of people, and red hair in 1.5%, and AB- blood in 0.6%, the combined probability (assuming independence) is 0.02 × 0.015 × 0.006 = 0.0000018, or roughly 1 in 555,000. Add left-handedness (10%) and you're at 1 in 5.5 million. Each additional rare trait dramatically increases your uniqueness.
Why Independence Matters (and Where It Breaks Down)
The multiplication method assumes traits are statistically independent — that having green eyes doesn't affect your blood type probability. This is mostly true for unrelated traits, but some traits correlate. Red hair and fair skin are genetically linked. Height and gender correlate. The Avortas calculator accounts for known correlations to give more accurate estimates.
Frequently Asked Questions
A combination is rare when the multiplied probabilities of its individual traits produce a very small number — typically below 1 in 1 million.