Final answer:
Behavior geneticists are most interested in the effects of nature and nurture on individual differences in personality, focusing on the interplay between genes and the environment.
Step-by-step explanation:
Assessing the relative effects of nature and nurture on individual differences in personality would be of most direct interest to c. behavior geneticists. Behavior geneticists focus on how individual differences arise through the interaction of genes and the environment.
They utilize approaches such as twin and adoption studies to discern the influence of inherited traits versus environmental factors on the development of personality. Furthermore, this field of study often intersects with the concept of epigenetics, which examines how gene expression is affected by external or environmental factors.