On the 21st and 22nd of May 1955 a congress of twins took place in Oirschot (Nederland). The initiative for this remarkable assembly came from the secretary of the local Sportsclub Orion, Mr. Louwers, who himself is a half of a twin. In order to add glamour to the anniversary of this club it was thought to achieve this by inviting twins. This gathering was a great success for over 300 twins from different countries took possession for several days of this quiet town in Brabant, The original intention was to offer a programme of social activities including excursions, musical evenings, competitions and dancing. The international Press had given a great deal of publicity to this Congress whiel from a cultural point of view was successful.

The total number of twins which took part was 327 (654 persons). The countries which were represented were as follows:

Holland, 229, Germany 61, Belgium 21, Saarland 4, Austria 4, France 2, Sweden 2, Switzerland 2, Finland 1, Italy 1. The average age of the participants was 29,1 years, the oldest being 82 and the youngest 15. Total number were 167 girls and 155 boys. The number of mixed twins was small (38) so that there as a rather strong tendency towards twins of the same sex. Similarly there was also a tendency for identical twins but this was not certain because not all the twins of the same sex could be actually identified by anthropological methods. After examination it was almost certain that 80 were one-egg twins but most probably there were more. This has strenghtened our opinion that also in the public eye only those twins are considered genuine which are physically and mentally the same. Since 375 twins had unselectively taken part, in the congress, it would have been expected that at least a 100 would have been mixed twins, in fact there were only 38.