I never said it could. It's just something that has to be very well controlled for and this article showed nothing to suggest it was in the studies it sort of cited.

It's entirely possible that the results in those studies you provided are solid. I don't know, I don't have the expertise or the access to go through them thoroughly, let alone run a replication. I would just urge everyone here to keep in mind that, as pointed out very well in aestra's comment above (https://hackertimes.com/item?id=7213317), this kind of research is subject to heavy cultural biases, both through the parents and experiments and through poor science reporting in the media.

And, even if it weren't, this Live Science linkbait blog post, the one rapidly climbing the front page of Hacker News with the sensationalist headline, is still uncited bollocks.

How could digit length ratio be affected by socialization or cultural biases?

All the subject if full of conflicting information. From Wikipedia: http://en.wikipedia.org/wiki/Digit_ratio

> Assuming a normal distribution, the 95% confidence interval for average length is 0.889-1.005 for males and 0.913-1.017 for females.

> In Manning's words, "There's more difference between a Pole and a Finn, than a man and a woman."

> 2D:4D is being used alongside other methods to help sex Palaeolithic hand stencils found in European and Indonesian caves.

if digit ratio were meaningless, why could it happen to predict toy preference?

other hormone effects, congenital adrenal hyperplasia can also be detected with blood tests, as was the case e.g. http://www.ncbi.nlm.nih.gov/pubmed/12414881

It couldn't. And I don't recall ever saying it could so I really don't see what you're getting at here.

"this kind of research is subject to heavy cultural biases"

"This kind" being the research we've been discussing, which is about socialisation and toy preference. Finger length and other easily-measured physical differences haven't been part of it.

It is in the studies I cited and in TFA.

It's briefly mentioned in the article as a possible indicator of toy preference because it correlates well with hormone levels. It clearly wasn't what the research, the discussion, or any of my comments were focusing on.

"as for those studies on young children"

It's reported in all of the child studies discussed in TFA. Fault the article if you want but "hormones" is in the title, and the whole point of the entire line of research is that it's implausible that prenatal hormone levels could be affected by cultural biases.

The hormone levels are unlikely to be affected by cultural biases but that's not the potential weakness I'm talking about in these studies. It's during the observation, through the eyes of the parents and scientists, of what toys the children are playing with where expectations can affect the results. On top of that, you've got biases affecting what studies get published and which of those then make headlines and get repeated in blog posts like this one.