A recent Trump executive order defines sex based on gamete size. But the order oversimplifies genetics, hormones and reproductive biology.

The president’s executive order signaled an intention to narrowly define the sexes, but experts say he is oversimplifying the ...

In one of Robert F. Kennedy Jr.’s first moves as secretary of the US Department of Health and Human Services, the agency ...

In everyday conversations, the terms 'sperm' and 'semen' are often used interchangeably. In biological terms, however, they ...

The Trump HHS defined "sex" as "a person's immutable biological classification as either male or female" based on reproductive sex cells.

Although scientists once theorized that all embryos start developing as females, recent research suggests that neither sex is "default." Legal experts told PolitiFact they see no basis for the claim ...

President Trump issued an executive order declaring that the U.S. government would only recognize a person’s sex assigned at birth.

The Trump administration had directed health agencies to place a notice condemning “gender ideology” on health webpages that ...

The executive order declares there are only "two sexes, male and female" and defines a "female" as "a person belonging, at conception, to the sex that produces the large reproductive cell." ...

Their analysis of male reproductive behavior reveals new findings. The rare males actively mated with females, just like typical males. However, genetic analysis confirmed that no male-derived ...