Dr. Debra Soh, author of "The End of Gender", joined "Fox News Primetime" Friday to discuss biological males participating in female sports and the advantages they have.

DR. DEBRA SOH: Individuals who are born male are on average larger, stronger, and faster than individuals born female. And even those trans individuals who are on hormone therapy -- so they are suppressing testosterone or on estrogen therapy – this does not override that structural foundation. It also does not change muscle mass or muscle strength after a year being on hormones--typically the guideline used for many sports. But I would argue it does not override the advantages that someone has from being born male.

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It's not fair. And it's absolutely heartbreaking when you listen to the girls and women who are competing against these individuals. They know before the competition starts what the outcome is going to be. They know they don't have a fair chance. It doesn't matter how hard they train, they know they are not going to be able to reach that level -- and even if you look at the average non-athlete male, depending on the sport; a non-transgender male, he will dominate even over elite female competitors.

WATCH THE FULL INTERVIEW BELOW:

Biological males have athletic advantage over females, 'it's not fair': Dr. Debra Soh

'Even if you look at the average non-athlete male, depending on the sport; a non-transgender male, he will dominate even over elite female competitors', Soh said