I got basketballs and golf clubs. I had to beg my dad to get me my first amiga 500. He agreed only because he thought I'd might get rich from it one day. So my interest, to the best that I can tell, was self originated.

You say the theories of biological ineptitude of women are not nonsense and then point to childhood socialization?

There is evidence that the games kids choose and how they react with each other has an effect though, and some of that seems to be affected by natural gender-sensitive bias.

Though while this might be large enough to be considered statistically relevant, nothing I've seen suggests a natural bias strong enough to account for more than a fraction of the mis-balance we see in later life in the science & technology arenas, so social pressure (even "accidental" pressure due to, as you suggest, the "toys" parents and other family buy), both at a young age and as kids progress through school, are presumably the larger factors by quite some margin.

There are natural gender biases, mental as well as physical, that are not caused by external cultural pressure, and to completely disregard that would be a mistake. But I think (caveat: going by my experiences here rather than any scientific study) in most cases that the difference between the average man and the average woman is smaller than the range of differences within each gender (so if you consider only the bulk of the population it might be valid to consider us identical overall).

I don't know about 20 years ago, but I think now there are pretty even numbers of girls who play games as boys who play games in my experience. I don't know how accurate that is for everywhere, but it doesn't appear to affect interest in programming. Of course, the boys aren't interested either, I think I'm the only one.

20 years ago was 1995, when Windows 95 was released. You might be off by a decade with the C64.

It seems that the decrease in women programmers seems to have started around the point where PC's supplanted mainframes. PC's were regarded as a toy by the established IT departments perhaps. I wonder if there is some correlation? I got a computer TI-994A because I was curious about programming due to those old Radio Shack comic books that showed what computers could do.

I have two girls, they play with Barbies - and do a helluva lot of other geeky /boy stuff like play Minecraft, program for fun, and get dirty outside. Stop the Barbie hate - some girls like pink and still will kick your ass.

But as you note -- the lack of interest isn't something inherent -- it's related to early experiences and expectations.

The kids probably got what they wished for.