Mongolism in Both of Twins of Opposite Sex

Mongolism in Twins.

It is now well established that persons with mongolism have an extra chromosome No. 21. Apart from a small proportion of cases in which a translocation is present, the anomaly is thought to arise from failure of a pair of No. 2I chromosomes to separate during meiosis in a gamete, or in an early mitotic division in a zygote. It was thought that a study of mongolism in twins might help to determi...

Paraplegia and mongolism in twins.

Opposite-Sex Twins and Adolescent Same- Sex Attraction

The etiology of human same-sex romantic attraction is generally framed in terms of (1) social influences, (2) genetic influences, or (3) hormonal influences. In this article, we show that adolescent males who are opposite-sex twins are twice as likely as expected to report same-sex attraction; and that the pattern of concordance (similarity across pairs) of same-sex preference for sibling pairs...

Birth weight in opposite sex twins as compared to same sex dizygotic twins.

The question addressed in the present report is whether the large birth weight differences in dizygotic twin pairs of opposite sex (DZos), especially in 'male first' couples--observed by Blickstein and Weissman (Blickstein I, Weissman A. Birth weight discordancy in male-first and female-first pairs of unlike-sexed twins. Am J Obstet Gynecol 1990;162:661-663) and replicated in the present study-...

Risk of Sex-Specific Cancers in Opposite-Sex and Same-Sex Twins in Denmark and Sweden.

BACKGROUND Increasing evidence shows that some cancers originate in utero. It is hypothesized that elevated exposure to some steroid hormones might increase cancer risk and that hormone transfer between twin fetuses could result in different prenatal exposure to testosterone. METHODS This large-scale prospective twin study compared opposite-sex (OS) and same-sex (SS) twins to test the impact ...