Do identical twins have the same / similar IQ?

No measurement is 100% accurate. If you measure a single persons iq twice, you generally don't get the same answer, so rather than talk about "the same" I'm going to talk about "similar". read more

Many scientific studies have looked at IQ between identical twins, and for the most part, identical twins have similar IQs. There can be some developmental differences due to environment during childhood, but adult identical twins typically have similar IQs. read more

No, even though twins do have identical DNA, they can have far different environments and life experiences. So, two identical twins though genetically the same could be very dissimilar in intelligence. read more

Identical twins have identical genes, whereas fraternal twins sharing on average half their genes. The twins shared environments, means researchers can separate genetic and environmental factors. The researchers found that certain regions of the brain were highly heritable. read more