And by the way we absolutely do know how to determine male from female scientifically.
The human X Y chromosome genomes have been mapped. We understand the genes, transcription factors, hormones and enzymes that determine human sex. The entire biochemical pathway of human sex development has been mapped. They've even mapped the mutations that lead to rare ambiguous sex determination. In fact the mutations are used in studies to elucidate the wild type pathways. The science and all.