Since Galton's work in 1875, twins have been utilized for hereditary investigation with the result that much work has been published on this subject. It has become increasingly important to the fields of biology and medicine that twins be thoroughly understood. Recent studies have become more detailed and many of the minute similarities and differences of twins are now known. With the advanced and increased interest in heredity, the various studies have also become more specialized and broken down into more detailed forms of investigation.
This paper is a statistical investigation of twins, using both identical (monozygotic) and fraternal (dizygotic) pairs. By means of the ERG (applying also color filters), comparative studies were made of twin sets, in an effort to determine whether there exists significant differences between the electroretinograms of monozygotic twins and dizygotic twins. A detailed discussion of the various origins of twinning and environmental factors is purposely
ZIV B. The Electroretinogram (ERG) in Human TwinsA Comparative Statistical Evaluation of the "b-Wave" of Identical and Fraternal Twins. AMA Arch Ophthalmol. 1960;63(2):243-245. doi:10.1001/archopht.1960.00950020245006