IQ is determined by:

is it by multiple genes and environmental factors?

Yes, IQ is determined by a combination of genetic and environmental factors. Research suggests that genetics plays a significant role in determining intelligence, with estimates suggesting that around 50-80% of IQ variations are due to genetic factors. However, environmental factors such as nutrition, education, socio-economic status, and early childhood development also have an impact on IQ. Both nature and nurture contribute to an individual's IQ.