A new study by Israeli researchers found that a man cannot become a woman by simply "identifying" as one and vice versa.
Geneticists from Israel's Weizmann Institute of Science discovered certain genes that are only expressed in women, while others are only expressed in men.
Professor Shmuel Pietrokovski and Dr. Moran Gershoni studied 20,000 genes, sorting them by sex, and searching for differences in expression in each tissue.
They eventually found around "6,500 genes with activity that was biased toward one sex or the other in at least one tissue, adding to the already major biological differences between men and women."
Some of the biggest differences were in genes responsible for body hair, fat storage, muscle building, and milk production for breastfeeding.
The researchers also found that biological sex also plays a role in preventing specific illnesses. For example, some genes expressed only in the left ventricle of the heart in women work to protect their hearts from disease until the women reach menopause. Another gene, in the liver, processes drugs differently according to the gender.
Essentially, their research means more than 21 percent of the entire human genome, which is composed of about 30,000 genes, are based on sex -- something a sex change operation and hormones cannot replace.
Mat Staver, founder and chairman of Liberty Counsel, says this research affirms God's creation.
"This recent study from Israel's Weizmann Institute of Science further proves that you cannot fool Mother Nature," Staver said. "The saying, 'I think, therefore, I am' is best left to philosophy and not science. Gender confusion is mental, not physical or biological. God made male and female and no amount of protestation will change the natural created order."