Complex sentence: Of these variables, only respondents' feelings about how masculine they were proved important, since the variable "Childhood Masculinity" was part of the "Childhood Gender Nonconformity" measure, which was more strongly correlated to adult homosexuality than any other variable.
Split into simpler sentences: Of these variables, only respondents' feelings about how masculine they were proved important. The variable "Childhood Masculinity" was part of the "Childhood Gender Nonconformity" measure, which was more strongly correlated to adult homosexuality than any other variable.