First cause isn't the same as the Big Bang. The Big Bang, or more accurately we should say nucleosynthesis, is an effect, not a cause. Popular Science (SciPop) promotes speculation about a possible first cause.
A Theory of First Cause
Origin of Gender
The Holy Trinity is the origin of gender. God refers to himself as male, Alpha, the Father. Jesus Christ, the begotten, is the Son. Simple deduction gives the gender of the Holy Spirit, Omega, to be female.
Holy Matrimony
Physical relationships between humans are, by their very nature, carnal. There's only one situation in which the sexual union of two people is sanctified: holy matrimony.