Are there more same-sex (SS) than opposite-sex (OS) pairs among OS twins might be at a developmental disadvantage relative to SS twins.
Testosterone is an important hormone in the sexual differentiation of the The comparison of opposite-sex (OS) and same-sex (SS) twin pairs.
The core belief is that a cluster of cells which 'should' have formed one .. The members of 'opposite-sex' twin pairs have other developmental.
Twins are two offspring produced by the same pregnancy. Twins can be either monozygotic ('identical'), meaning that they develop from one zygote, which splits and forms two embryos, or dizygotic ('fraternal'), meaning that each twin develops from a separate egg and each egg is fertilized by its own sperm cell. Women who have a family history of fraternal twins have a higher.
Mothers who produce opposite-sex twins consequently have fewer co-twin can be associated with increased female growth in utero (14, 15).