The Frequency of Recurrent Multiple Maternities Using Two Sets of Census Data in Japan: 1990 and 1995

Imaizumi, Yuji; Nishida, Etsuo

doi:10.1375/twin.10.4.638

Cited by 3 publications

(4 citation statements)

References 8 publications

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“…DZ twins occur when two separate oocytes, released during the same menstrual period, are fertilized by separate sperm cells [1]. MZ is rarer than DZ twinning except in Japan [5] and no maternal, genetic, or environmental factors have been associated to it so far [6]. On the other hand, DZ twinning is a phenomenon of complex etiology, in which both genetic predisposition and environmental factors play a role [7].…”

Section: Introductionmentioning

confidence: 99%

Twin Town in South Brazil: A Nazi's Experiment or a Genetic Founder Effect?

et al. 2011

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Cândido Godói (CG) is a small municipality in South Brazil with approximately 6,000 inhabitants. It is known as the “Twins' Town” due to its high rate of twin births. Recently it was claimed that such high frequency of twinning would be connected to experiments performed by the German Nazi doctor Joseph Mengele. It is known, however, that this town was founded by a small number of families and therefore a genetic founder effect may represent an alternatively explanation for the high twinning prevalence in CG. In this study, we tested specific predictions of the “Nazi's experiment” and of the “founder effect” hypotheses. We surveyed a total of 6,262 baptism records from 1959–2008 in CG catholic churches, and identified 91 twin pairs and one triplet. Contrary to the “Nazi's experiment hypothesis”, there is no spurt in twinning between the years (1964–1968) when Mengele allegedly was in CG (P = 0.482). Moreover, there is no temporal trend for a declining rate of twinning since the 1960s (P = 0.351), and no difference in twinning among CG districts considering two different periods: 1927–1958 and 1959–2008 (P = 0.638). On the other hand, the “founder effect hypothesis” is supported by an isonymy analysis that shows that women who gave birth to twins have a higher inbreeding coefficient when compared to women who never had twins (0.0148, 0.0081, respectively, P = 0.019). In summary, our results show no evidence for the “Nazi's experiment hypothesis” and strongly suggest that the “founder effect hypothesis” is a much more likely alternative for explaining the high prevalence of twinning in CG. If this hypothesis is correct, then this community represents a valuable population where genetic factors linked to twinning may be identified.

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Section: Introductionmentioning

confidence: 99%

Twin Town in South Brazil: A Nazi's Experiment or a Genetic Founder Effect?

et al. 2011

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“…According to Imaizumi and Nishida (2007), the repeat frequency of twins in the Okinawa District was higher than in eight other districts. From Table 4, the TFR indicated the highest value in the Okinawa District among the nine districts.…”

Section: Figurementioning

confidence: 90%

“…To date, however, no such data is available. Imaizumi (2001) estimated the number of Japanese twin pairs less than 16 years of age using two sets of census data in 1990 and in 1995, as well as the frequency of repeated twinning using these same census data sets (Imaizumi & Nishida, 2007).…”

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confidence: 99%

Estimated Number of Siblings in Japanese Families with Multiple Birth Children using Two Sets of Census Data: 1990 and 1995

Imaizumi¹,

Nishida

2011

Twin Res Hum Genet

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The purpose of this study was to estimate the number of siblings in each Japanese family with multiple birth children using two sets of census data, from 1990 and 1995. The mean number of siblings for singletons was 2.3 in 1990 (2.4 in 1995), 2.9 (2.9) for one set of twins, 4.6 (4.5) for two sets of twins, and 3.5 (3.3) for one set of triplets. For birth order of multiples, the highest mean sibling number was 4.4 for one set of twins (the middle), 7.5 for two sets of twins (the middle-middle), and 4.3 for one set of triplets (the last). The mean sibling number was slightly higher for like-sexed twins and triplets than in unlike-sexed twins and triplets. The mean sibling number was highest in the Okinawa District, among nine districts (0.4 for singletons, 0.6 for one set of twins, 1.0 for two sets of twins and 0.6 for triplets). The current study of the number of siblings in each family with multiple birth children will help provide data for designing programs to help support multiple-birth families. The method of using census data on multiple births might result in a system to analyze nationwide data on multiple birth children if there is no national registry of multiple births after live births in any country.

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“…This frequency is strongly associated with the twinning rate in the population (Andersen, 1980;Eriksson, 1973;Puech, 1877;Weinberg, 1901). Recently, Imaizumi (2007) reported that in Japan, with its well-known low twinning rate, the repeat frequency among couples was under 1%. In our opinion, because the data sets from Saxony are so large, and the twinning rate at that time was between 12 and 13 per 1000 maternities, additional occurrences are quite plausible.…”

Section: Methodsmentioning

confidence: 99%

Sex Ratio in Sibships With Twins

Fellman¹,

Eriksson

2008

Twin Res Hum Genet

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In national birth registers of Caucasians, the secondary sex ratio, that is, the number of boys per 100 girls at birth, is almost constant at 106. Variations other than random variation have been noted, and attention is being paid to identifying presumptive influential factors. Studies of the influence of different factors have, however, yielded meagre results. An effective means of identifying discrepancies is to investigate birth data compiled into sibships of different sizes. Assuming no inter- or intra-maternal variations, the distributions of the sex composition are binomial. Varying parental tendencies for a specific sex result in discrepancies from the binomial distribution. Over a century ago, the German scientists Geissler and Lommatzsch analyzed the vital statistics of Saxony, including twin maternities, for the last quarter of the 19th century. They considered sibships ending with twin sets. Their hypothesis was that in sibships ending with male–male twin pairs, the sex ratio among previous births is higher than normal, while in sibships with female–female twin pairs, the sex ratio is lower than normal. If the sibship ended with a male-female pair, then the sex ratio is almost normal. Consequently, a same-sex twin set indicated, in general, deviations in the sex ratio among the sibs within the sibship. Our analyzes of their data yielded statistically significant results that support their statements.

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The Frequency of Recurrent Multiple Maternities Using Two Sets of Census Data in Japan: 1990 and 1995

Cited by 3 publications

References 8 publications

Twin Town in South Brazil: A Nazi's Experiment or a Genetic Founder Effect?

Twin Town in South Brazil: A Nazi's Experiment or a Genetic Founder Effect?

Estimated Number of Siblings in Japanese Families with Multiple Birth Children using Two Sets of Census Data: 1990 and 1995

Sex Ratio in Sibships With Twins

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