Which one of the following statements most accurately represents the findings of twin studies?

	a.	When identical twins are reared apart, their IQs are found to be highly correlated.
	b.	Differences in adult intelligence are roughly 50 percent hereditary.
	c.	Identical twins who grow up in the same family have poorly correlated IQs.
	d.	Identical twins who are reared together differ by as much as 50 IQ points.