Transgender cyclist who dominated championships defends winning world title after Donald Trump Jr. called 'BS' on her victory

Rachel McKinnon, the transgender female cyclist who won first place at the Masters Track Cycling World Championships on Saturday, issued a full-throated defense of her title after one of President Donald Trump's sons called into question the legitimacy of her performing as a woman in women's sports.

What are the details?

McKinnon took home the gold medal on Saturday, reviving an ongoing debate about whether biological men who have decided to transition to female should be permitted to participate in women's sports.

Donald Trump Jr. took to Twitter where he addressed the controversy, calling McKinnon's win "BS."

Sharing a story about McKinnon and the recent competition, he wrote, "This BS will destroy women's sports and everything so many amazing female athletes have worked their entire lives to achieve."

"I could care less how you identify," he continued, "but this isn't right."

He later doubled down on his initial remarks and expressed his regret to "all female athletes who spent their lives mastering their games."

What did McKinnon say?

In a series of tweets, the transgender cyclist defended what she believes is her right to participate in the competitions as a woman.

"I'm just going to come out and say it: My body doesn't produce testosterone anymore," she insisted. "And it hasn't for nearly a decade. Draw your own conclusions."

She also pointed out that her critics don't have a problem with testosterone levels, anyway, but with trans women at large.

"Psst. I was competing prior to the IOC's 2015 update to their trans policy," McKinnon said. "I met the older, more restrictive 2003 policy. Y'all don't have a problem with testosterone levels, you have a problem with trans women period. Lowering the testosterone limit won't affect me."