Internal and external environmental factors ... traits are expressed in individuals of only one sex. An example of a sex-limited trait is lactation, or milk production. Although the genes for ...

Sitting in my doctor's examination room, I was surprised when she told me, "Genetics don't really matter for chronic disease.

Threshold traits don't follow the basic Mendelian rules; they're influenced by many genes and by the environment. What does this complexity lead to? Francis Galton had a strong desire to explain ...