Imagine That a Researcher Measures a Specific Psychological Characteristic (SPC)

Imagine that a researcher measures a specific psychological characteristic (SPC) in pairs of siblings who are being reared together. She finds a correlation of .15 between pairs of adopted siblings who are biologically unrelated, a correlation of .63 for fraternal twins, and a correlation of .92 for identical twins. These results suggest that

A) compared to the impact of the environment, genetics contributes relatively little to variability in the SPC.
B) the shared environment contributes greatly to the variability in the SPC only among the identical twins.
C) both the environment and genetics contribute substantially to the variability in the SPC.
D) relative to the influence of genetics, the environment contributes relatively little to variability in the SPC.