I think this is an assumption made to justify a premise. I think this is a reflection of a deep-seated societal expectation of masculinity and femininity, and the assumption that a person in today's world who identifies as a woman must be more feminine than the average male.
I don't think this is a good assumption. Under the ideology of gender identity as currently pushed, I don't think this assumption would hold up at all.
I would think of it more an an unconfirmed observation.
I think that if it were not the case, we would be seeing an awful lot more cases of males winning girls' sporting events.
I'm going to present some numbers I ran across a bit ago, because it connects indirectly to this topic.
There are approximately 115,000 high school seniors in the state of Michigan.
According to one article I read, 0.7% of people 18-24 identify as trans
gender. Assume for the moment that the high school seniors identify as transgender at the same rate. That would mean there were 805 transgender high school seniors in Michigan. The article had no information about prevalence of MtF vs. FtM transitioners. Lets' assume half. 4,02 males who identify as female.
I also compared scores of boys and girls on the Presidential Fitness Challenge. The score for the 100th percentile in 17 year old girls for the mile run was the same as the 90th percentile for boys. In other words, 10% of the boys could beat the highest score for girls. I'm going to assume some roundoff error and drop that to 9%. That would mean 36 males could beat the fastest female.
So, if they went out for track, the top 36 positions at the girls' state championships would be occupied by males.
Obviously, something is wrong with those numbers, because what I described isn't happening. We have talked a lot about Terry Miller and Andraya Yearwood because those two are the only high profile examples among high school students. We also have very few examples in professional, college, or Olympic competition. Those numbers I presented suggest that we ought to be seeing complete dominance of women's and girls' sports by transgenders. We aren't seeing that, except in isolated cases, so what's wrong with the numbers?
To address your issue, I think one of many things wrong with those numbers is that I don't think that transgirls are equally distributed throughout the male athletic ability spectrum. I think you would find that transgirls are generally in the lower 50% of male athletic ability, with very few in the top 10%, where they would dominate the females.
Now, for the broader picture, think about those numbers. Legislators, primarily from the GOP, have been sounding the alarm about the end of women's sports if transgirls are allowed to compete against females. If those numbers were anywhere near close to correct, those GOP legislators would be correct.
Fortunately, I think there are several things wrong with those numbers. I think the number of transgenders is much less than the 0.7% claimed. I think they had to, at the very least, throw a lot of Qs from LGBTIQ into the transgender pot in order to come up with a number that high. I think FtM is more common than MtF. Since many (I have no idea how many) 17 year old transgirls take hormones, that reduces the athletic ability somewhat among those that do. I think that transgirls generally start out with a lower distribution of athletic ability (i.e. transgirls are found less frequently among accomplished male athletes than among the general population of males). I think that among the transgirls who could win competitions against females, a fair number choose not to, for a variety of reasons.
So, for all those reasons, we are not seeing complete dominance by transgender male athletes in women's and girls' sports. But the numbers I described were enough to give me pause that I might indeed be underestimating the threat to girls' athletics. I think I would like to see some addressing of the issue from the TRA side. Right now one thing that keeps males out of girls' athletics are social stigmas about competing, or indeed about acknowledging trans identities. TRA's are trying to end those stigmas. What will be the effect if they are successful? Terry Miller and Rachel McKinnon might just be the tip of the iceberg. What sort of issues would we see if people felt more free to identify publicly as transgender, were not pressured into taking hormones if they didn't feel comfortable at that time in their lives, and did not feel constrained by social pressure to avoid competing against females?
In my previous arguments I've never really addressed it, because I never thought it was all that important. Selena Soule and Alanna Smith are individuals, not representatives of some class of people, and I think their concerns are legitimate even if there are very few people with similar circumstances, but I must admit if there were tens of thousands of people in similar circumstances (i.e. females losing against males in girls' athletic competitions) I think that would be influential to a lot of people. Based on the numbers of transgenders, it might actually be that this problem is bigger than I previously thought, and the people sounding the alarm might actually have a point.