It discusses research supporting the claim that fetal testosterone level relates to characteristics of autism. They followed kids and found that those who were exposed to higher levels of testosterone in utero had more characteristics of autism (though none actually had autism):
New research shows that male hormones in the womb are linked to social and emotional skills in childhood
The researcher's call it the "extreme male brain" hypothesis of autism, arguing that autism is about an intense interest in patterns (they call it systems) and lower social skills. They say the following:
(B)oys and girls who had higher levels of foetal testosterone were significantly more likely to have a large number of autistic traits.
This is where I get confused, because higher levels of fetal testosterone are recognized to affect other characteristics, too. They note that in utero testosterone is functional on birth order:
The extreme male brain hypothesis (is that) girls tend to show better empathy and boys tend to have a stronger interest in systems. Children with autism seem to have an exaggerated version of typical male preferences. They have a strong interest in systems and have difficulty empathising.
So, what is this related to? Homosexuality. This article notes, for example: Having older brothers a factor in boys becoming gay. All right, then, let's look at homosexuality and fetal hormone levels. This article (about finger length), notes:
There is some evidence, for example, that mothers who have previously conceived several sons expose subsequent foetuses to higher levels of male hormones.
What's going on? It seems that higher levels of masculinizing hormones increase the probability of men being (1) hypermasculized, (2) gay, and (3) autistic-like less empathic. Can that be? The social stereotype is clearly that women like gay men because they're so in tune with their feminine side, which would seem to mean hyperfeminized (not hypermasculinized) and more empathic than normal men. Hell, there are books and books and books about it. Maybe it's time to admit we don't know dick about hormones and behavioral characteristics (although continued research is encouraged). Note, for fun, the first article's comment about correlations and third variable explanations:
(G)ay men did appear...to have been exposed to higher levels of fetal androgens...(The) findings point more toward gay men as hypermasculinized.
Title reference here.
Professor Baron-Cohen cautioned that the results do not prove that the link between male hormones and autistic traits is causal – both could be the result of something else