I wrote some of the best, most creative code of my life in the first 6 months after my son was born. I was focused, and yet could work on multiple project simultaneously very effectively.

I got hardly any sleep, so if that is "being a slave to my hormones" I'm all for it!

Either way, I think it is fair to say that the effects or parenthood are very unpredictable.

You'll need to offer studies establishing a causal relationship between testosterone levels and technical/business success for the difference to mean anything.

For all we know lower testosterone levels may lead to a heightened business acumen.

It obviously does not affect everyone in the same way, but as a generalization, I would say that becoming a parent clearly makes one a more responsible person.