The immediate global impressions of zygosity (based upon physical similarity) were recorded by the investigator at initial meetings with 105 pairs of twins. The accuracy of these ratings, as well as classifications provided by two objective procedures (physical resemblance questionnaire; dermatoglyphic analyses) and two subjective procedures (parental impressions; physician's impressions), were evaluated by comparison with results from bloodtyping for 53 pairs. The judgments of the investigator furnished the most accurate indication of zygosity (94-96% accuracy). Laboratory tests were repeated for five pairs when the results proved incompatible with the investigator's ratings. In all five cases, the investigator's judgments were confirmed, indicating that a laboratory error had occurred. It appears that the opinion of a skilled observer of twins can provide a convenient and highly effective alternative to bloodtyping.

Revelations about twins are abundant, but the information often is inaccessible. Therefore, The Twins Foundation, a multifaceted, international, nonprofit agency has been formed. Through development of a Research Library, Museum and Hall of Fame, it will (1) provide archival and research support to the growing number of disciplines involved in twin studies; (2) provide a central repository and clearing house of information about twins for the general public; (3) enlist twin achievers to act as role models for adolescent twins; and (4) collect information about the contributions twins have made to their societies in order to dispel still prevalent negative stereotypes about multiples. (Note: The term “twin” is used generically and implies all multiples).