Influences on Intelligence

Which of the following have been shown in twin studies (check all that apply)

Which of the following is NOT true (check only ONE)

Research indicates that cognitive abilities are substantially influenced by our genes.  Approximately how much of the variance in cognitive abilities can be attributed to genetic factors?

The steady increase that has been shown over the past few decades in people’s average performance on an IQ test is also known as 

Thinking about the Flynn effect give 3 possible reasons for the increase in IQ scores over the past few decades.