A study was conducted on twinning in relatives of consecutive triplet sets in the Åland Islands in the years 1740-1939. The incidence of twinning in sibships of triplets was extremely high, 80/1000 (56/1000 before and 143/1000 after the triplet maternity). In Finland as a whole, 1905-1954, the twinning rate was among mothers of triplets 38/1000, ie, about 2.6 times the rate in general population, and was higher after (48/1000) than before the triplet maternity (34/1000). In the sibships of fathers of triplets there was a low rate of twinning (below 10/1000) both of same-sexed (SS) and of opposite-sexed (OS) triplets. Among sibships of mothers of OS triplets the twinning rate was 18/1000 and among mothers' sibships of SS triplets 26/1000. The series of triplet families from both Åland and Finland as a whole indicate a considerably higher frequency of twinning on the maternal than on the paternal side. The sibships of OS triplets in Finland have higher twinning rates than sibships of SS triplets (50/1000 vs 27/1000). In sibships of triplets, not only the DZ but also the MZ twinning rates were approximately twice as high as those in the general population. The triplet rates in Finland were increasing strongly with maternal age and were in the last century among mothers of 30-39 years of age considerably higher than among mothers from this century. This, in combination with higher mean parity, may explain the high rates of multiple maternities in sibships of triplets in the past. The rate of triplet maternities seems to be more sensitive to sociodemographic changes than the rate of twin maternities. Mothers of triplets in Finland had a high frequency (more than 40%) of prenuptially conceived firstborn children. This, and a short protogenesic interval indicate that triplet-prone mothers are more fecundable, ie, they conceive with greater ease and/or may have a better physical condition than other women for completing a gestation with multiple embryos.

This study examined sleep patterns in twins, paying special attention to the mirroring phenomenon. Concordance and discordance of sleep related patterns (parasomnias) in a group of 27 monozygotic (MZ) mirror image twins were compared to sleep patterns in a group of 53 MZ non-mirror image twins and a group of 24 dizygotic (DZ) twin pairs. Sleep patterns had the lowest concordance among MZ mirror twins. “Mirroring” was observed not only in facial features but also in some physiological patterns such as sleep and sleep deviations. These facts suggest that mirroring in MZ twins is not merely a superficial epiphenomenon, but a reflection of a biological polarization. Biological polarization in this context is a descriptive term emphasizing the role of biological (physiological, biochemical or even genetic) versus psychological or environmental factors causing not only mirror body image but opposite tendencies in the development of personality, professional and sex orientation and, most importantly, the opposite presentation of pathology.

Following some observations on the pathogenesis and clinical manifestations of « Xeroderma Pigmentosum «, two histologically ascertained cases are reported, as studied in the dermosyphilopathic Clinic of Berlin's Free University.

In the first case it was possible to prove parental consanguinity, already mentioned by Siemens as proof of irregular recessive inheritance. In the second case the lack of sufficient familial information suggests a non-genetic origin. In both cases it was possible to rol out venereal disease as the causin factor, and the disease appeared only after the third year of age, at 10 years in one case, with onset at the cornea. In the latter case the EEG reveals variations indicating the existence of organic brain disturbances which (associated with the ocular alterations) suggests the occurence of a neuroectodermosis.

In any case it would be wise to warn Xeroderma patients that in the case of consanguineous marriage, there is the danger of the recessive disease (latent in both parents) becoming real; otherwise the physician may, after such a marriage, support the possible request for sterilization on the part of the patient.

A case report is presented with a prolonged interval between delivery of 25 days. A quintuplet pregnancy resulted from hormonal stimulation of ovulation. Two fetuses remained after an embryo reduction was performed at 11 weeks gestation. At 22.5 weeks gestation the first twin (310 g) was delivered after spontaneous rupture of membranes. Using tocolytic agents, the second twin (710 g) was born at 26 weeks of gestation. This case is discussed and a review of the literature is given.

From the whole of genealogical researches on the people of B., P. and Al. towns, we came to the following conclusions:

1) the monomeric recessive autosomal transmission of hydrophtalmos, with a high degree of penetration, has been confirmed;

2) a type of congenital cataract with monomeric recessive autosomal hereditary transmission, with a comparatively reduced degree of penetration, has been located;

3) in towns B. and P. affected lines of hydrophtalmos and congenital cataract have been located;

4) the first definite heterozygotes for hydrophtalmos in town B. and for hydrophtalmos and congenital cataract in town P. have been located: they date back to the first half of the 18th Century;

5) the date of hydiovariation's inception has been located at about two or three generations before, or around the middle of the 17th Century.

This paper expresses new views regarding the origin and relatioships of the African Pygmies, based on a study of a small colony at Bundibugyo in Western Uganda which apparently differ in no respect from the Efé Pygmies. Compared with them are the Bwamba, a tribe examined at Bundibugyo and Fort Portal who are found to be pygmoids, of relatively recent hybrid origin from crosses between the Pygmies and forest Negroes. Their intermediate stature and great variability confirm the hybrid origin.

Citation of early literature shows that the Pygmies formerly occupied a much wider area, including the Cameroons, Sierra Leone and probably Liberia in West Africa, where they first came to the attention of Europeans in the 16th Century. The Eastern Pygmies first came to be known about 1870 by expeditions up the Nile into the Azande country where they found the Monbuttu Negroes and the Akka Pygmies. The ancient Egyptians knew the Akka.

The Bambuti Pygmies are now recognized as having three branches, Efé, Basúa and Aká of similar dwarf stature, the differences between them being of minor character. The upper limit for Pygmy stature is generally regarded as 150 cm. Surrounding the Ituri forest Pygmies are many pygmoid tribes of taller stature, produced by miscegenation with the forest Negroes. Groups extend east to the Semliki River and south as far as Lake Kivu and even Lake Bangweolo. The adjacent Negro (Bantu) tribes in these eastern areas show various degrees of hamitization.

Accounts are given of early as well as later European contacts with Pygmy tribes, and of certain groups taken to Europe.

The extensive observations of Schebesta and Gusinde have made the Bambuti Pygmies best known. For these people Gusinde adopts the name Twiden, which may be shortened to Twi. He shows that some of the eastern Pygmies and pygmoids have recently undergone great changes in their manner of life.

The unique symbiotic relations between Pygmies and their Negro overlords are well known. They hunt in the forest for okapi, elephants and other animals, supplying meat to the Negroes, who give them bananas in return. When the banana was introduced to Africa from India is unknown, but there must have been an earlier period when the Pygmies fed themselves, and perhaps lived in open territory northeast of where they now extend. The Singa fossil skull gives possible evidence of such former extension.

The pantropical disease Kwashiorkor, is seen in the Pygmies, the brick-red hair being a symptom. It apparently results from protein deficiency, and especially from a diet of bananas at the time of weaning. The Pygmy teeth and jaws are probably the most pathological to be found in any human race.

Racial mixture with the Negroes is considered. Forest Negroes frequently take a Pygmy wife, whose children become “Negroes”. The Pygmies thus remain pure except for occasional unofficial mixing. The F1 hybrids are intermediate in stature and probably in other characters. They backcross to the Negro and are thus absorbed into that race. A small number of genes, without dominance, for each racial character-difference is probably involved. The Balese and Babira Negroes are much pygmyized.

Study of skin colour in Pygmies, Baambas, Hottentots and Negroes shows that the Gates chart of skin colours is applicable to these races. The Pygmies correspond with No. 3 (mahogany) of the chart, the Baambas (Pygmy X Negro) with No. 2 (dark mahogany), the Hottentot-Bush with No. 4 (yellow), and the Negro with No. 1 (black). Thus the gene R, under which was formely included both black and mahogany, is divided into two – Q representing the black of the Negro, and R representing the mahogany of the Pygmy. S (yellow) and T (brunet) skin are present in the Bush-Hottentot. The full black Negro is then QQRRSSTT, the Pygmy RRSSTT and the Bush-Hottentot SSTT. The colour chart, derived only from Negro-White crosses is thus directly applicable to the other African races.

Certain evolutionary relationships of the Pygmies, Negroes and Bushmen now seem clear. The Pygmies are of ancient origin, with mahogany skin and hairy body. The Negroes have since acquired a black skin by the Q mutation, and their bodies have become hairless by one or more loss mutations. The common ancestor of Pygmy and Negro would be a tall race with the mahogany skin and hairy body of the Pygmies. This race may now be extinct. The Bush, with sallow yellow skin, must have lost the ancestral mahogany gene in addition to their other transformations.

The Pygmy dwarfing is apparently the result of a single gene mutation of essentially achondroplastic type, as suggested in 1946. This kind of mutation is not very uncommon in Negro-tribes (various cases are cited) and Has probably been occurring, like melanism in moths, for thousands of years. Interbreeding of such heterozygous dwarfs would quickly establish a tribe more or less homozygous for the dwarf gene. The Pygmies are then the oldest living race in Africa with the exception of the Bushmen.

The blood groups and sickling of the Pygmies are considered in relation to other African races.

Measurements show that the Pygmy skull is frequently little smaller than that of the Negro, their ranges apparently overlapping, although some Pygmy skulls are very small in dimensions. The cephalic index is higher than that of the Negro in accordance with the small stature, and frequently approaches closely to brachycephaly or overlaps it in the female. In morphology the Pygmy head is ovoid, but skulls are frequently more or less markedly pentagonoid. This suggests a common Boskopoid origin of Pygmies and Bushmen. The Pygmy nose is very primitive and characteristic. Various other morphological features of the skull are considered. The Pygmy teeth and jaws are the worst in any human race, the alveoli being sometimes eroded away completly. This may have a nutritional basis.

The armspan in the living Pygmy exceeds the stature, but the proximal segment of both limbs is relatively very short. The bones of the skeleton are generally smaller in all dimensions than in the tall races, but the head is relatively large, and the same is frequently true of the pelvic girdle. Thus we have a form of achondroplastic dwarfing of mutational origin. Many kinds of dwarfing occur in man, some normal, some pathological. The Pygmy type is one of these but “normal”.

1. The proportions of red haired offspring within families in which one or both parents are red haired are too high to support the hypothesis that red hair is inherited as a simple recessive trait.

2. Family data and gene frequency analysis give strong support to the hypothesis that red pigment in human hair is dominant to its absence, and is hypostatic to brown and black.

The low birthweight of twins compared with singletons is only slightly influenced by the higher congenital abnormality rate in twins, or the increased incidence of proteinuric pre-eclampsia in the mothers. Reduced intakes of energy food or of zinc, copper, and iron do not account for the lower birthweight. The main cause of low birthweight is preterm delivery, and this is more common in monozygotic than dizygotic twin pregnancies, due particularly to premature rupture of the membranes. The type of placentation did not influence the preterm onset of labor. Preterm labor in monozygotic twin pregnancies is associated with a very high boy:girl ratio, but this did not apply in dizygotic twin pregnancies.

This is a follow-up study aiming to describe personality development of twins and possible differences at different ages. The investigation was conducted at the Mother Clinic in the Karolinska Hospital in Stockholm. This report describes the language development of 35 twin pairs at 9 months of age. The development values show that no greater differences exist for girls between twins and singletons. The language result is however lower. The boys, on the other hand, have considerably lower results both on total development scale and on the language scale.

1. The Author has investigated on a twin material of 34 twin pairs the papillary line patterns on the fingers, the interdigital areas of the palms, and the hallucal area of the soles according to a systematics accounted for by the Author in earlier works.

2. The diagnosis of zygosity has been based on a comparison for the morphological particularities and on blood group analyses, in the cases in which the relative chance for dizygosity for the concordant pairs has been calculated.

3. The frequency distribution for the papillary line patterns of the twin pairs showed no significant divergence with respect to the large Swedish population, earlier investigated.

4. The 19 MZ twin pairs showed a concordance of 84.2-89.5% for the total qualitative value, total ridge-count and for the hallucal patterns.

Data concerning 16 triplet and higher-order deliveries (resulting in a total of 56 infants) are reviewed. The vaginal delivery rate was 81%. Maternal morbidity was more serious after abdominal delivery. Prematurity (< 36 weeks gestation) rate amounted to 68%. Overall perinatal and neonatal mortalities for infants born after 28 weeks gestation and weighing at least 1000 g were 7% and 3%, respectively. We doubt that neonatal outcome could have been markedly improved by performing more cesareans. The importance of antenatal care is stressed.

The decline of the twinning rate in Germany since 1900 is exclusively due to a fall of the DZ rate. The analysis of the birth data in Baden-Württemberg from 1955 to 1972 shows that the decline of the DZ twinning rate can be explained only to a small extent by the shift of the maternal age-parity distribution towards younger mothers and lower parities. It appears reasonable that the greater part of this decline is caused by the lessening prevalence of the more fecundable, DZ twin-prone women due to the growing influence of family planning. Furthermore, it is imaginable that the probability for multiple ovulation is decreased after cessation of hormonal contraception.

While traveling in East Africa, three typical cases of hairy ears were observed incidentally in natives of India, two of whom were from Goa. The inheritance in all three cases was compatible with location of the gene in the Y-chromosome. Two other independent cases have been reported to me from the same general part of India, southeast of Bombay, which indicates a considerable frequency of the gene in this area.

The only previously known pedigree of this condition came from Italy in 1907, and several independent cases in males are described in the early Italian literature. In all these Italian families the hairy ears were associated with insanity or other psychiatric conditions, but this association may have been fortuitous, and hairy ears may be as frequent in Italy as in India.

A scoring method for the diagnosis of Turner's syndrome (T.S.), based on five dermatoglyphic and four skeletal characteristics, showing significant frequency variations between patients and normal females, is presented. The dermatoglyphic characteristics include: total finger ridge count, ab ridge count, maximal atd angle, T line terminating in the second interdigital interval, and presence of hypothenar patterns. The skeletal characteristics include: carpal sign, metacarpal sign, phalangeal sign, and abnormally shaped distal phalanges. Arbitrary score numbers have been assigned to each characteristic, depending on the magnitude of the difference between patients and controls; the partial scores were added up to form the final T.S. score. The diagnostic value of T.S. score has been proved, since it is well separating the patients from normal females. The probability that an individual with a given T.S. score has the Turner's syndrome has been estimated.

Temperament differences between cotwins at least 15% discordant for birth-weight were compared for a group of 66 preterm twin pairs and a group of 70 fullterm twin pairs, assessed in the neonatal period. The assessment focused on irritability, resistance to soothing, activity, reactivity, and reinforcement value. For the most part, significant differences were not obtained between discordant preterm cotwins. Previous research [10] had demonstrated that the larger fullterm twin of discordant pairs was more irritable, more difficult to soothe, more active while awake and during sleep, less reactive to visual and auditory stimuli, and less reinforcing to the examiner than the smaller cotwin. It was concluded that, for the behavioral variables measured, the fullterm group is at higher risk than the preterm group, and that both the lighter and the heavier discordant twins displayed signs of early behavioral risk. The findings suggested that the continued gestation for cotwins discordant in weight may be a risk period for early temperament development of the twins.

Scores from a behavioral assessment of 160 stable preterm newborn twins were compared with those obtained from 120 full-term newborn twins. The twins were examined during various activities to obtain representative samples of behavior in the following behavioral categories: irritability, resistance to soothing, reactivity, reinforcement value, and activity level. Within-pair correlations were found in all of the behavioral categories, suggesting a constitutional influence on behavioral patterns during the neonatal period. The preterm infants demonstrated internal consistency of behavior similar to that of the full-term group in the first three categories. However, group differences were found when comparing the preterm with the full-term infants on actual ratings of the items. Behavioral differences between these full-term and preterm twins were comparable to those published for samples of singleton infants.

This study is based on 145 pairs of twins included in a longitudinal study of a cohort of singletons born in 1953 and living in the Stockholm metropolitan area in 1963. Of these 145 pairs, 28 were classified as MZ, 103 as DZ and 14 pairs could not be classified. School achievement and ability test results have been collected for this group as well as data for the boys from physical and mental examinations on enrollment to military service. The purpose of this study was to compare within-pair similarity for MZ and DZ twins from birth onwards. There seems to be a divergent trend over time for MZ twin pairs to become more similar and DZ twin pairs to become less similar in height growth, school achievement and verbal ability. This is in accordance with previous research in this field. In relating similarity within pairs to birthweight, we found a drop in within-pair similarity for low birthweight MZ and DZ twin pairs (both twins ≤2.500 g), but not for normal weight twin pairs. A discussion is initiated concerning methodological implications of these results.

A family of Iranian-Jewish origin with two hereditary enzymatic defects in the red blood cells, catalase deficiency and glucose-6-phosphate dehydrogenase deficiency, is described. The two enzymatic defects were inherited independently of each other. The findings are compatible with a transmission of the catalase deficiency by an autosomal gene of incomplete dominance, the homozygous state resulting in severe catalase deficiency and the heterozygous state in intermediate catalase deficiency.

The author agrees with earlier writers that most of the differences observed in monozygotic pairs are due to unusual or extreme environmental factors acting before or during the twins' birth. Although they are typical of development in twins, these environmental factors can hardly be considered typical of development in other individuals. This point, as a review of the literature shows, is often overlooked by those who study twins in the childhood or adult age ranges. As a result the inferences drawn from twin differences are frequently mistaken, or at least quite exaggerated so far as the significance of postnatal influences in non-twins is concerned. At the same tihe, if allowance is made for the environmental biases peculiar to twin studies, the findings may be said to establish more about the importance of heredity in the medical and behavior sciences than most investigators have thought. In the author's opinion the largest single source of bias is the mutual circulation that exists during prenatal development of the majority of monozygotic pairs. Data on that circulation's difference-producing effects are reviewed and related to studies of mature twins. Effects of lateral inversions (asymmetry reversals) and of “natal” factors (chiefly conditions of delivery) are also reviewed, and methods of judging the importance of all three of the biasing conditions are outlined. Need for obtaining systematic and complete information about the natal factors is stressed.

The frequency of living twins born in Southern Moravia in the period 1960-1970 was studied and found to be 0.67%. No differences in twinning rate due to the years, seasons, districts or towns with 10,000 and more inhabitants in comparison with other localities, were found. An interesting hitherto undescribed phenomenon of twin-birth clustering in space and time was observed.