Testosterone is an important hormone in the sexual differentiation of the brain, contributing to differences in cognitive abilities between males and females. For instance, studies in clinical populations such as females with congenital adrenal hyperplasia CAH who are exposed to high levels of androgens in utero support arguments for prenatal testosterone effects on characteristics such as visuospatial cognition and behaviour. The comparison of opposite-sex OS and same-sex SS twin pairs can be used to help establish the role of prenatal testosterone.
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What genetic influences occur in utero with fraternal twins of opposite sexes? Does the male's testosterone have an effect on the developing female and vice versa? I seem to be ambidextrous with some tasks and my index finger is shorter than my ring finger.
A survey carried out in Finland found that boy and girl twins were more developed than both same-sex sets and singleton children. The researchers involved, from the University of Jyvaeskylae, suggest that the best qualities of each assist the progress of the other. Traditionally, twins are thought to take longer to develop certain social, emotional and language skills.
About 32 out of every people is a twin. Identical twinning seems to be due just to chance. The percent of people who are twins differs by race and ethnicity.
Twin brothers Raymon and Richard Miller are the father and uncle to a 3-year-old little girl. The problem is, they don't know which is which. Or who is who.
Back to Your pregnancy and baby guide. In recent years, fertility treatments and the fact women are having babies later has made multiple births more common. Identical twins are always the same sex, so if your twins are identical, you'll have 2 girls or 2 boys.