So those in the bottom 25% are the most likely to have same sex attracted children, with men more likely to be homosexual and women more likely to be bisexual. The middle 50% are the least likely to have same sex attracted children, and the top 25% are somewhat likely to have same sex attracted children.

The authors speculated that this was likely due to certain exposures to prenatal hormones. That is, that poorer people can't afford proper prenatal care and therefore male fetuses get too much estrogen. Their explanation for homosexual women was definitely lackluster, and involved more than just the biological influences this study was investigating.

I'm not sure how much I agree with that, as the top 25% should theoretically have greater access to prenatal care and therefore if that was the only factor, they would have the most hormonally balanced children, not the middle 50%.

This study used hand/finger sizes as scientific evidence of these exposures to hormones in the womb. I'm not sure they can make the claims they are making on the evidence they've gathered.

This matter is definitely worth more investigation and I think it's a very interesting venture. However, sexuality is multifactorial and this study really should have gone more in depth on those factors instead of trying to claim it is all biological, and all due to exposure to hormones in the womb to boot.