I see nothing ridiculous or wrong with transgender people competing with non-transgender people in sex/gender specific sports, under a gender classification that is opposite to the gender the person had at birth. Such is partly due to the scientific information I have read. Here are some of my reasons.
1) Simon said "If it were genuine, why are there never born-women transgenders entering the mens competitions?" But in actuality there are people (at least one person I read about) born female (no one is born as an adult and thus no one is born a woman) who became an full grown woman and later became transgender and who later competed in men's competition. Do you want proof? Well here is some proof.
Visit https://en.wikipedia.org/wiki/Transgender_people_in_sports . It says the following.
"The first out transgender person to make a US National Team was Chris Mosier, who in 2016 qualified for Team USA in duathlon. Mosier is considered the catalyst for the change in the IOC policy on transgender athletes in 2015, when he challenged the policy after initially being banned from the world championship race. Mosier also became the first known transgender athlete to compete in the Olympic Trials in the gender with which they identify, and the first trans man to make a men's Olympic Trials, when he competed in January 2020 in the US Olympic Team Trials in the 50k Racewalking event. " That person (born female) thus competed in men's competitions.
The next paragraph in the article says "In 2017 Mack Beggs, a teenager from Texas, was required to wrestle against girls throughout the season of his transition from female to male up through the state championship, despite wanting to wrestle against boys. This was due to state sport regulations requiring athletes to compete alongside athletes of their assigned sex. Some opponents say the testosterone prescribed as part of his transition gives him an unfair advantage and made it unsafe for the other wrestlers. (He finished the regular season at 52–0 and won the state championship.)" That person thus wanted, and tried to obtain permission, to compete in boy's/men's competition but he was barred from doing so.
2) Regarding what sex we are born as, that is mostly a result of the effects of the sex hormones in our bodies. Yes our sex chromosomes is a major factor, but that is because our sex chromosomes influence what our sex hormones will be and their levels. But also androgen hormones secreted by the mother during pregnancy (especially if she previously gave birth to multiple boys prior to becoming pregnant with a female) can influence a genetically female baby in the womb to be born with more masculine characteristics than would otherwise be case, and such females in many cases end up becoming "tom boys".
The International Olympic Committee (IOC) Medical Commission now recognizes that the sex hormone levels are a much more relevant factor in determining sex/gender for sport's competitions, than the sex chromosomes. In regards to that note the following from the article.
"In 2003, a committee convened by the International Olympic Committee (IOC) Medical Commission drew up new guidelines for participation of athletes who had undergone gender reassignment. The report listed three conditions for participation. First, athletes must have undergone sex reassignment surgery, including changes in the external genitalia and gonadectomy. Second, athletes must show legal recognition of their gender. Third, athletes must have undergone hormone therapy for an appropriate time before participation, with two years being the suggested time.
It was not until 2004 that the IOC allowed transgender athletes to participate in the Olympic Games.
Sports organizations have sought a test for sex verification to ensure fairness across all sports. This began in the 1940s with "femininity certificates" provided by a physician. In the 1960s, visual genital inspections were used to confirm gender, followed by chromosomal analysis to detect the presence of the SRY and DYZ1 genes, normally found on the Y chromosome. These tests were all designed to ensure that athletes were only allowed to compete as their sex, but mostly resulted in the exclusion of intersex athletes.
More recently, testosterone levels have become the focus and, at the same time, new guidelines have been sought that would allow successfully-transitioned athletes to compete. Since the proposition in 2003 to use testosterone levels, reputable organizations such as the IOC have adopted strict policies that employ testosterone as a metric to allow successfully transitioned female athletes to compete. More recent guidelines have focused entirely on testosterone levels, such as the IOC’s current guidelines, originally set in November 2015, which set limits on transgender athletes’ testosterone levels for them to be permitted in women’s competition categories. Controversy surrounding the 2020 Tokyo Olympics also centered around testosterone levels, specifically over whether the IOC’s guidelines should be amended to set stricter testosterone limits, although this proposed change has been strongly debated. The testing of testosterone alone as a marker for athleticism has been debated."
3) There are genetically male babies who are born looking female (at least on the outside) and who are thus raised as girls, but who upon entering puberty naturally become completely boys. Such happens because sometimes the bodies of genetically male young children do not respond adequately to (and/or produce an adequate amount of) the male sex hormones in their bodies, and thus appear to be females, until the male sex hormone levels increase dramatically during puberty. I learned such from watching two science programs on PBS TV.
I intend to say more later.