14. How can heritability affect a person's intelligence? 15. How can fluid intelligence change over time?

14. Many researchers believe that IQ has a reaction range, which refers to the limits imposed on IQ by heredity. The IQ that a person can achieve is limited by hereditary factors, which set an upper and lower limit. The environment determines where a person's IQ falls within these
ranges.
15. Fluid and crystallized intelligence change over time, with different mental abilities peaking at different times. Fluid intelligence has long been thought to peak in childhood, but new research published in 2015 suggests that some aspects of fluid intelligence may peak as late as age 40.