In the beginning of our civilization, yes. Less so in recent millennia, however. I was involved in one project that might have opened up whole new avenues of temporal technology. But the project was [a disaster] cancelled.

[And Narvin still sounds disappointed in how all that turned out, even though it was centuries ago.]

Beyond that, TARDISes continue to improve, there are minor developments in computers, in medical technology...but no major breakthroughs. The professors at the Academy said that it was because we'd reached the edge of knowledge itself. [But it hadn't been a very satisfying answer to young Narvin, who'd desperately wanted to achieve some technological feat on the level of Rassilon's innovations. To be told "sorry, boy, it's all been done, there's nothing left for you" had been a disappointment.]

Population control largely takes care of itself. But just in case, there are legal quotas and limits to how many cousins a House can loom.